Important Questions For You!
The thing with CBSE class 10 science is that: either you are very good at it or you struggle with it a lot. In either way, we can help you score more in CBSE Class 10 Board exams. Have you taken a good look at the syllabus?
CBSE Class 10 Science highlights important concepts which include chemical reactions, principles, equations and a lot more. TopperLearning provides study materials for CBSE Class 10 Science which offers a systematic way to prepare for the final examination. Take our study notes, for example.
The CBSE Class 10 science notes summarize all the key points of a particular chapter in the syllabus so that you can glance through them any time you want. It’s the easiest way to revise the key learnings of every chapter in the class 10 syllabus for CBSE science without even opening your Class 10 science book.
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Chapter 1: Chemical Reactions and Equations
1. Why are decomposition reactions called the opposite of combination reactions? [1M]
2. When potassium chlorate (KClO3) is heated in the presence of manganese dioxide catalyst, it decomposes to form potassium chloride and oxygen gas. Represent this in the form of a balanced chemical equation. [1M]
3. A solution of potassium chloride when mixed with silver nitrate solution forms an insoluble white substance. Write the chemical reaction involved and mention the type of chemical reaction. [3M]
4. Equal lengths of Mg ribbon are taken in test tubes A and B. Hydrochloric acid is added to test tube A, while acetic acid is added to test tube B. In which case the reaction would occur more vigorously and why? Write the chemical equations for reactions in test tubes A and B. [3M]
5. Describe an activity to show the decomposition reaction of ferrous sulphate in the laboratory. [3M]
6. A solution of substance 'X' is used for white washing. [3M]
- Name substance 'X' and write its formula.
- Write the reaction of substance 'X' named in (i) above with water.
- Write the balanced equation for the following chemical reaction:
Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
7. [5M]
a. Write chemical equations for the reactions taking place when
- Zinc sulphide is heated in air.
- Zinc carbonate is calcined.
- Manganese dioxide is heated with aluminium powder.
b.
- What happens when a strip of lead metal is placed in a solution of copper chloride? Write the balanced chemical equation for the eaction along with the colour changes observed during the reaction.
- What are precipitation reactions? Give one example of a precipitation reaction.
8. [5M]
- A water-insoluble calcium compound (A) on reacting with dil. H2SO4 released a colourless and odourless gas (B) with brisk effervescence. When gas (B) was passed through lime water, the lime water turned milky and again formed compound A. Identify A and B, and write the chemical equations for the reactions involved.
- A brown substance 'X' on heating in air forms a compound 'Y'. When hydrogen gas is passed over 'Y', it changes to 'X' again.
- Name substances 'X' and 'Y'.
- Name the processes occurring during the two changes.
- Write the chemical equations involved.
Chapter 2: Acids, Bases and Salts
1. Fresh milk has a pH of 6. How do you think pH will change as it turns into curd? Explain. [1M]
2. Classify the following into acidic oxides and basic oxides: Na2O, SO2, MgO, CO2. [1M]
3. [3M]
- Write the chemical name and formula of washing soda. How is it prepared? Write the chemical equation of the reaction.
- Why should Plaster of Paris be stored in a moisture-proof container?
- If we have hydrochloric acid and acetic acid in equal concentration, which will be the stronger acid and why?
4. Define 'water of crystallisation'. [3M]
Give two examples of substances having water of crystallisation.
Write their chemical formulae.
5. [3M]
- Name the compound which is obtained from baking soda and is used to remove the permanent hardness of water.
- Write its chemical formula.
- What happens when it is recrystallised from its aqueous solution?
6. [3M]
- What change will you observe in the colour of red litmus paper when it is dipped into a solution of sodium sulphate? Give reason to explain your observation.
- A bottle filled up to the brim with concentrated sulphuric acid is left open in the atmosphere by mistake. Will there be any change in the level of liquid? Explain your answer with reasons.
7. [5M]
a. Write word equations and balanced equations for the reaction taking place when
- Dilute sulphuric acid reacts with zinc granules
- Dilute hydrochloric acid reacts with magnesium ribbon
b. What is meant by 'hydrated' and 'anhydrous' salts? Explain with examples.
c. Give two important uses of washing soda.
8. [5M]
a. Write the chemical equation for the preparation of
- Bleaching powder
- Plaster of Paris
- Caustic soda
b. What is the chlor-alkali process? Give two uses of NaOH obtained from this process.
9. Give suitable reasons for the following statements: [5M]
- Rain water conducts electricity, whereas distilled water does not.
- We feel a burning sensation in the stomach when we overeat.
- On rubbing a tarnished copper vessel with lemon or tamarind juice, it begins to shine again.
- A solution of sodium carbonate is not acidic.
- Dry ammonia has no effect on litmus paper, whereas a solution of NH3 in water has.
Chapter 3: Metals and Non-Metals
1. What happens when iron nails are kept in an aqueous solution of CuSO4? [1M]
2. Name a non-metal which is lustrous and a metal which is non-lustrous. [1M]
3. What are amphoteric oxides? Give two examples. Element X on reaction with oxygen forms a dioxide XO2, which turns blue litmus red. Is element X a metal or a non-metal? [3M]
4. [3M]
- What are the two main allotropes of carbon?
- Distinguish these two allotropes on the basis of hardness and electrical conduction.
5. What happens when [3M]
- Zinc reacts with copper sulphate
- Magnesium reacts with HCl
- Sodium reacts with water
6. [5M]
- Write the electronic configurations of sodium and chlorine.
- Show the formation of sodium chloride from sodium and chlorine by the transfer of electrons.
- State the type of bonding formed.
- List two properties of the compounds formed by this bonding.
Chapter 4: Carbon and its Compounds
1. Write the name of the following compound. Name the acid and alcohol from which it might be prepared. [1M]
2. Name the functional group present in each of the following organic compounds: [1M]
- CH3COCH3
- C2H5COOH
3. What is meant by a homologous series of carbon compounds? Classify the following carbon compounds into two homologous series and name them. [3]
C3H4, C3H6, C4H6, C4H8, C5H8, C5H10
4. [5M]
- State two properties of carbon which lead to a large number of carbon compounds.
- Explain isomerism. State any four characteristics of isomers. Draw the structures of possible isomers of butane, C4H10. Also,explain why we cannot have isomers of the first three members of the alkane series.
Chapter 5: Periodic Classification of Elements
1. How were the positions of cobalt and nickel resolved in the modern periodic table? [1M]
2. What are lanthanides and actinides? [1M]
3. How does the metallic character of elements change along a period of the periodic table from left to right and why? [2M]
4. How does the modern periodic law justify one position for isotopes? [2M]
5. State Mendeleev’s periodic law. Which group of elements was missing from Mendeleev’s original periodic table? Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his periodic table? [3M]
6. How could the modern periodic law remove various anomalies of Mendeleev’s periodic table? Explain with examples. [3M]
7. Atoms of eight elements—A, B, C, D, E, F, G and H—have the same number of electronic shells but different number of electrons in their outermost shell. Elements A and G combine to form an ionic compound which can also be extracted from sea water. This ionic compound is added to a small amount of almost all vegetables and dishes during cooking. Oxides of elements A and B are basic in nature, while those of elements E and F are acidic. However, the oxide of element D is almost neutral. Based on the above information, answer the following questions: [5M]
- To which group or period of the periodic table do these elements belong?
- What would be the nature of the compound formed by a combination of elements B and F?
- Which two of these elements could definitely be metals?
- Which one of the eight elements is most likely to be found in the gaseous state at room temperature?
- If the number of electrons in the outermost shell of elements C and G are 3 and 7, respectively, write the formula of the compound formed by the combination of C and G.
8. Explain: [5M]
- Larger the atomic size, more metallic is the element.
- Size of the atom changes when it loses or gains electrons.
- K is more reactive than Li.
- Electronegativity of Cl is higher than S.
- Group 17 elements are non-metals, while Group 1 elements are metals.
9.
Select from the table:
- Which is the most electronegative?
- How many valence electrons are present in G?
- Write the formula of the compound between B and H.
- In the compound between F and J, what type of bond will be formed?
- Draw the electron dot structure for the compound formed between C and K.
Chapter 6: Life Processes
1. Why do fish die when taken out of water? [1M]
2. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms? [1M]
3. How do guard cells regulate the opening and closing of stomata? [2M]
4. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration? [2M]
5. Why is small intestine longer in herbivores as compared to carnivores? [2M]
6. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds? [3M]
7. What are the different ways in which glucose is oxidised to provide energy in various organisms? [3M]
8. How are fats digested in our body? Where does this process take place? [3M]
9. [5M]
- Draw a well-labelled diagram of the human digestive system.
- Describe the role of the following in the process of digestion:
(i) Bile (ii) Salivary amylase (iii) HCl
10. [5M]
- Define excretion.
- Name the basic filtration unit present in the kidney.
- Draw the excretory system in human beings and label the organs of the excretory system which perform the following functions:
- forms urine
- is a long tube which collects urine from the kidney
- stores urine until it is passed out
11. [5M]
- Mention any two components of blood.
- Trace the movement of oxygenated blood in the body.
- Write the function of valves present in between the atria and ventricles.
- Write one structural difference between the composition of arteries and veins.
Chapter 8: How do Organisms Reproduce?
1. Name one sexually transmitted disease each caused by bacterial infection and viral infection. [1M]
2. Where does fertilisation take place in human females? [1M]
3. A couple wants to space the birth of their second child. Suggest one preventive method which could be observed? [1M]
- By the husband
- By the wife for the same
4. Differentiate between self pollination and cross pollination. [2M]
5. What is the function of the Cowper's gland and prostate gland? [2M]
6. What is vegetative propagation? State two advantages and two disadvantages of this method. [3M]
7. Name the process by which amoeba reproduces. Draw the various stages of its reproduction in a proper sequence. [3M]
8. List any four methods of contraception used by humans. How does their use have a direct effect on the health and prosperity of a family? [3M]
9. Mention the post fertilisation changes that occur in a flower. [3M]
10. [5M]
- List three differences between sexual and asexual types of reproduction.
- Explain why variations are observed in the offspring of sexually reproducing organisms.
11. [5M]
- Write the function of the following parts in the human female reproductive system:
(i) Ovary (ii) Oviduct (iii) Uterus - Describe in brief the structure and function of the placenta.
12. [5M]
- Distinguish between cross-pollination and self-pollination. Mention the site and product of fertilisation in a flower.
- Draw a labelled diagram of a pistil showing the following parts: Stigma, Style, Ovary, Female Germ Cell
Chapter 9: Heredity and Evolution
1. Why is DNA copying necessary during reproduction? [1M]
2. Mendel crossed a pure white recessive pea plant with a dominant pure red flowered plant. What will be the first generation F1 hybrids? [1]
3. A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plant bearing white flowers. What will be the result in the F1 progeny? [1M]
4. Why did Mendel choose pea plant for his experiment? [2M]
5. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not? [3M]
6. State the three Mendel's laws of inheritance. [3M]
7. Give the basic features of the mechanism of inheritance. [5M]
8. [5M]
- ‘Sex of children is determined by what they inherit from the father and not from the mother.’ Justify.
- Explain the result of a monohybrid cross.
Chapter 10: Light - Reflection and Refraction
1. Which mirror is used as a rear-view mirror in vehicles? [1M]
2. If the radius of curvature of a spherical mirror is 60 cm, what is its focal length? [1M]
3. What is the nature and position of the image when an object is placed at the focus of a concave mirror? [1M]
4. If a magnification of -1 is to be obtained using a convex lens of focal length 6 cm, then the object must be placed [1M]
- within 12 cm
- at 6 cm
- iat 12 cm
- beyond 12 cm
5. Draw a neat and labelled ray diagram when an object is placed in front of a convex mirror between infinity and the pole. [3M]
6. What is the speed of light in a medium of refractive index 1.8 if its speed in air is 300000 km/s? [3M]
7. Define refractive index. If light enters from air to glass having a refractive index 1.5, then calculate the speed of light in glass. [3M]
8. Describe the Cartesian sign convention for a spherical lens. Draw a neat and labelled diagram to illustrate the sign convention. [3M]
9. If a concave mirror has a focal length of 15 cm, find the two positions where an object can be placed to give, in each case, an image twice the height of the object. [3M]
10. Draw a diagram to represent a convex mirror. On this diagram, mark the principal axis, principal focus F and centre of curvature C if the focal length of a convex mirror is 5 cm. Also, comment on the characteristics of the image if an object is placed 15 cm from the mirror. [5M]
11. [5M]
- Two lenses A and B have a power of +3 D and –4 D, respectively. What is the nature and focal length of each lens?
- A combination of lens contains two converging lens of focal length 30 cm and 50 cm and a diverging lens of focal length 40 cm. Find the power and focal length of the combination.
Chapter 11: Human Eye and the Colourful World
1. Why does the Sun appear white at noon? [1M]
2. What is meant by dispersion of white light? [1M]
3. In the formation of spectrum of white light by a prism: [2M]
- which colour is deviated least?
- which colour is deviated most?
4. What is Tyndall effect? Explain with an example. [3M]
5. Why does the sky appear blue during the day and red at sunset? [3M]
6. Draw and explain the dispersion of white light through a prism. Also, comment on the deviation, wavelength, frequency and speed of the dispersed light. [5M]
7. Write a short note on the formation of a rainbow with a neat and labelled diagram. [5M]
Chapter 12: Electricity
1. Define electric power and state its SI units. [1M]
2. The values of potential difference V applied across a resistor and the corresponding values of current I flowing in the resistor are given below: [2M]
- What is the nature of the V-I graph plotted for the above values of potential difference and current?
- Which law is illustrated by such type of graph?
3. What are the factors on which the heating effect of electric current depend? Explain with a practical example. [3M]
4. State and explain Ohm’s law with a graph. [3M]
5. What is resistivity? State the factors on which it depends. [3M]
6. Resistors of 8 Ω and 12 Ω are connected in parallel to each other, while a resistor of 6 Ω is connected in series to a 6-V battery. Calculate: [5M]
- Total resistance of the circuit
- Total current in the circuit
- Total potential difference across the 6-Ω resistor
Draw a neat and labelled circuit diagram for the same.
7. An electric iron draws 2.4 amperes of current from a 240-V source. Find [3M]
- Resistance of the electric iron
- Power consumed by the electric iron
8. Give reasons for the following: [5M]
- Filament-type electric bulbs are not power efficient.
- Coils of heating devices are made of alloys rather than pure metals such as copper.
- An electric bulb is not filled with normal atmospheric air but is filled with argon or nitrogen.
- Metals such as copper and aluminium are used on a large scale for the transmission of electricity.
- Parallel combination is preferred over series combination for connecting electric appliances in houses.
9. [5M]
- Derive the expression for heat produced due to current (I) flowing for a time period (t) through a resistor (R) having a potential difference (v) across the terminals.
- Name the relation. List all the variables along with their SI units.
- How much heat will an instrument of 14 W produce in half an hour if it is connected to a battery of 70 V?
Chapter 13: Magnetic Effect of Electric Current
1. What is the effect on magnetic field strength produced at a point near a straight conductor if the electric current flowing through it increases? [1M]
2. What were the observations made by Oersted in his experiment of current-carrying conductors? [1M]
3. If a current-carrying conductor is kept in a magnetic field, it experiences a force. List the factors on which the direction of this force depends. [3M]
4. Explain Fleming’s right-hand rule and left-hand rule. [3M]
5. What is a magnetic field? List characteristics of a magnetic field. If two magnetic field lines intersect at a point, what does that indicate? [3M]
6. Define and explain the phenomenon of electromagnetic induction. [3M]
7. A coil of insulated copper wire is connected to a galvanometer. What happens if a bar magnet is [3M]
- Pushed into the coil
- Withdrawn from the hollow space of the coil
- Held stationary inside the coil
8. Explain with a neat sketch the working of an electric motor. [5M]
Chapter 15: Our Environment
1. Why should biodegradable and non-biodegradable wastes be discarded in two separate dustbins? [1M]
2. In the following food chain, 20,000 J of energy was available to plants. How much energy would be available to man in this chain? [1M]
Plants → Sheep → Man
3. You being an environmentalist are interested in contributing towards the conservation of natural resources. List two activities that you can do on your own. [1M]
4. Why is it necessary to ban the use of plastic bags? [2M]
5. Give reason why a food chain cannot have more than four trophic levels. [2M]
6. What are the adverse effects of combustion of fossil fuels on the environment? List any two steps you would suggest to minimise environmental pollution caused by burning of fossil fuels. [3M]
7. How is ozone formed in the upper atmosphere? Why is damage to the ozone layer a cause of concern to us? What causes this damage? [3M]
8. Explain the phenomenon of ‘biological magnification’. How does it affect organisms belonging to different trophic levels, particularly the tertiary consumers? [3M]
9. What is a food chain? Why is the flow of energy in an ecosystem unidirectional? Explain briefly. [3M]
10. [3M]
- Why should national parks be allowed to remain in their pristine form?
- Why is the reuse of materials better than recycling?
11. Explain some harmful effects of agricultural practices on the environment. [5M]
ASSERTION – REASONING QUESTIONS
Two statements are given - one labelled Assertion (A) and the other labelled Reason (R).
Select the correct answer to these questions from the codes (i), (ii), (iii) and (iv) given below.
- Both A and R are true, and R is the correct explanation of the assertion.
- Both A and R are true, but R is not the correct explanation of the assertion.
- A is true, but R is false.
- A is false, but R is true.
Chapter 1: Chemical Reactions and Equations
1. Assertion: Aluminium foil is commonly used for packing food preparations.
Reason: A coating of aluminium oxide is deposited on the metal surface and protects it against corrosion.
2. Assertion: When carbon dioxide gas is passed through lime water, a white precipitate is initially formed.
Reason: White precipitate is of calcium carbonate which is formed during the reaction.
3. Assertion: In the electrolysis of water, the volume of hydrogen liberated is twice the volume of oxygen formed.
Reason: It is because water has hydrogen and oxygen in the ratio 1:2.
4. Assertion: Silver chloride turns grey in sunlight.
Reason: Silver chloride decomposes into silver and chloride by light.
5. Assertion: Copper can easily displace silver on reacting with an aqueous solution of silver nitrate.
Reason: Silver can be easily precipitated since it is insoluble in water.
Chapter 2: Acids, Bases and Salts
1. Assertion: Reaction of zinc granules with dilute sulphuric acid releases a gas with a pop sound.
Reason: When a metal reacts with an acid, it releases water vapour.
2. Assertion: An acid is a substance which contains one or more hydrogen atoms in its molecule.
Reason: An aqueous solution of acid turns blue litmus red.
3. Assertion: Acetic acid is a weak acid.
Reason: Acetic acid gets partially ionised in aqueous solution.
4. Assertion: Milk of magnesia is taken to get rid of pain in the stomach during indigestion.
Reason: Milk of magnesia is a base and it neutralises the excess acid in the stomach.
5. Assertion: Dry HCl gas does not change the colour of litmus paper.
Reason: Dry HCl gas can behave as an acid.
Chapter 3: Metals and Non-metals
1. Assertion: Metals can be drawn into wires and reshaped.
Reason: Metals are ductile and malleable.
2. Assertion: Rusting of iron does not take place in ordinary water.
Reason: Ordinary water contains dissolved oxygen.
3. Assertion: Positive ions are known as cations.
Reason: Cations are released at the anode.
4. Assertion: When zinc nitrate reacts with aluminium, aluminium nitrate is formed.
Reason: Aluminium is more reactive than zinc.
5. Assertion: Sodium chloride is not soluble in water.
Reason: Electrovalent compounds are generally soluble in water.
Chapter 4: Carbon and its Compounds
1. Assertion: Diamond is the hardest crystalline allotropic form of carbon.
Reason: Carbon atoms in diamond are tetrahedral in nature.
2. Assertion: A large number of carbon compounds exists due to the self-linking property of carbon known as catenation.
Reason: Strength of carbon to carbon bonds is very high.
3. Assertion: During fermentation, glucose is converted to ethyl alcohol with the help of the enzyme maltase.
Reason: Alcoholic fermentation is carried out by certain enzymes present in yeast.
4. Assertion: Zinc nitrate reacts with aluminium.
Reason: Aluminium is more reactive than zinc.
5. Assertion: Sodium chloride is not soluble in water.
Reason: Electrovalent compounds are generally soluble in water.
Chapter 5: Periodic Classification of Elements
1. Assertion: Chlorine is the most reactive member of the halogen family.
Reason: Size of the chlorine atom is greater than that of the fluorine atom.
2. Assertion: In the long form of periodic table, the elements are arranged in order of increasing masses
Reason: The properties of the elements are related to the atomic number.
3. Assertion: In a triad, the three elements present have the same gaps of atomic masses.
Reason: Elements in a triad have similar properties.
4. Assertion: Tendency to lose electrons will decrease across a period.
Reason: Effective nuclear charge increases across a period.
5. Assertion: Boron and silicon have the same properties.
Reason: Boron and silicon are in the same block.
Chapter 6: Life Processes
1. Assertion: Diffusion does not meet the high energy requirements of multicellular organisms.
Reason: Diffusion is a fast process but only occurs at the surface of the body.
2. Assertion: Saliva contains an enzyme called amylase.
Reason: Amylase helps to break down simple sugars like glucose into complex molecules like starch.
3. Assertion: Bile helps in the emulsification of fats.
Reason: Bile makes acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it.
4. Assertion: The inner lining of the small intestine has numerous finger-like projections called villi.
Reason: Villi increase the surface area for absorption.
5. Assertion: Rings of cartilage are present in the throat.
Reason: They ensure that the air passage does not collapse.
Chapter 8: How do Organisms Reproduce?
1. Assertion: Reproduction enables the continuity of life for generations.
Reason: Reproduction is a biological process in which an organism gives rise to young ones similar to itself.
2. Assertion: Paramoecium reproduces by budding.
Reason: All unicellular organisms reproduce by asexual methods.
3. Assertion: Errors during DNA copying are a source of variations.
Reason: Variations are useful for ensuring the survival of the species.
4. Assertion: Tail of the sperm consists of an acrosome and mitochondria.
Reason: Acrosome contains enzymes which assist in fertilisation.
5. Assertion: Contraceptives can be effectively used for population control.
Reason: They can be used to avoid unwanted pregnancy in females.
Chapter 9: Heredity and Evolution
1. Assertion: In a monohybrid cross, the F1 generation indicates dominant characters.
Reason: Dominance occurs only in the heterozygous state
2. Assertion: The father is responsible for the sex of the child.
Reason: Boys inherit the Y chromosome and girls inherit the X chromosome from the father.
3. Assertion: Mendel was successful in his hybridisation experiments.
Reason: Garden pea proved ideal experimental material.
4. Assertion: Mendel chose pea plant for his experiments.
Reason: Pea plant provides diverse visible traits and has a short life span.
5. Assertion: When TT and tt pea plants were crossed, only tall plants were obtained in F1 progeny.
Reason: This was because tall allele was dominant over the dwarf allele.
Chapter 10: Light - Reflection & Refraction
1. Assertion: Concave mirrors are used in torches.
Reason: The light bulb placed at the focus of the concave reflector produces a strong beam of light.
2. Assertion: Magnification produced by a concave mirror of focal length 10 cm for the object distance 15 cm and image distance 30 cm is –2.
Reason: The image formed by a concave mirror is always real, inverted and magnified irrespective of the position of the object.
3. Assertion: When a beam of light is incident on a glass slab perpendicularly, there is no refraction.
Reason: The rays of light which fall perpendicularly on the glass slab reach, enter and leave the glass slab at the same instant of time.
4. Assertion: When the direction of the rays of light is reversed, they retrace their path.
Reason: According to the dual theory of light, light is a particle and a wave simultaneously.
5. Assertion: When we stand close to the convex mirror our image is virtual, erect and diminished.
Reason: When object lies anywhere between pole and infinity of convex mirror, the image formed is virtual, erect and diminished.
Chapter 11: Human Eye and the Colourful World
1. Assertion: The Sun appears for about two minutes even after it has set below the horizon.
Reason: The refraction of light rays coming from the Sun is caused by the Earth’s atmosphere.
2. Assertion: Red colour light after dispersion is deviated the most.
Reason: Red colour has the maximum speed in a glass prism.
3. Assertion: White light splits up into seven colours on passing through a transparent medium.
Reason: Dispersion of white light occurs because the colours of white light travel at the same speed through the glass prism.
4. Assertion: The Sun appears white when it is overhead in the sky.
Reason: Light coming from the Sun has to travel a relatively shorter distance through the atmosphere to reach us.
Chapter 12: Electricity
1. Assertion: The property of a conductor due to which it opposes the flow of current through it is called resistance.
Reason: The resistance of a conductor depends on thickness and temperature.
2. Assertion: Electrical wires are made of copper or aluminium.
Reason: Copper and aluminium have very low electrical resistance.
3. Assertion: If the length of the wire is doubled, the resistance gets doubled.
Reason: Resistance of a conductor is inversely proportional to its length.
4. Assertion: Nichrome wire is used to make the filament of an electric bulb.
Reason: Nichrome does not undergo oxidation even at a high temperature.
5. Assertion: In a parallel combination of circuits, each appliance has its separate switch and thus can be switched on/off independently.
Reason: In a parallel combination, each appliance gets the same voltage as that of the power supply.
Chapter 13: Magnetic Effect of Electric Current
1. Assertion: Motion of a charged particle under the action of the magnetic field is not always with constant speed.
Reason: Magnetic force does not have any component either along or opposite to the direction of the charged particle.
2. Assertion: Current generated by powerhouse generators reverses its direction after equal intervals of time.
Reason: Direct current can be transmitted for long distances without much loss of electric current.
3. Assertion: When a bar magnet is held stationary inside the coil, there is no deflection in the galvanometer.
Reason: If there is no relative motion between the magnet and the coil, the current will not be induced in the coil.
4. Assertion: The magnitude of the current induced in the coil can be increased by increasing the number of turns in the coil.
Reason: By reversing the direction of motion of the coil, the direction of current can be reversed.
5. Assertion: Freely suspended current carrying solenoid comes to rest in N-S direction just like a bar magnet.
Reason: On one end of current carrying straight solenoid behaves as a North pole and other end as a South pole.
Chapter 15: Our Environment
1. Assertion: Ecology is the study of the relationship between living organisms and their environment.
Reason: The biotic community and the non-living environment of an area function together to form an ecosystem.
2. Assertion: Producers are called nature’s recyclers.
Reason: They produce food by photosynthesis and make it available to other links of the ecosystem.
3. Assertion: Food chains are limited to 4-5 trophic levels.
Reason: The flow of energy within trophic levels follows the 10% law.
4. Assertion: Most air conditioning units are not eco-friendly.
Reason: They cause ozone depletion.
5. Assertion: Plastic is biodegradable.
Reason: Biodegradable substances can be broken down by biological processes.
PARAGRAPH BASED QUESTIONS
1. Read the following and answer any four questions from (i) to (v) Newlands’ Law of Octaves In 1864, Newlands arranged the known 56 elements in the order of increasing atomic masses. He observed that the properties of every eighth element are similar to the properties of the first element. Based on this observation, he proposed the Law of Octaves for the classification of elements.
Law of Octaves: When the elements are arranged in the increasing order of their atomic masses, the properties of every eighth element are similar to the first.
Many limitation were found in Newlands’ octaves. This law was found to be applicable only up to calcium. Newlands fitted all the known elements in a table of 7 X 8 that is 56 boxes. Newlands placed two elements each in some boxes to accommodate all the
known elements in the table. For example, Co and Ni, Ce and La. Moreover, he placed some elements with different properties under the same note in the octave. For example, Newlands placed the metals Co and Ni under the note ‘Do’ along with halogens, while Fe, having similarity with Co and Ni, away from them along with the nonmetals O and S under the note ‘Ti’. Also, Newlands’ octaves did not have provision to accommodate the newly discovered elements. The properties of the new elements discovered later on did not fit in the Newlands’ law of octaves.
i) Newland’s rule known as _____________ .
- Law of triad
- Law of octave
- Law of periodic table
- Periodic law
ii) Newland’s law of octaves based upon_______ .
- Increasing order of atomic number
- Increasing order of atomic mass
- Increasing order of electron
- Increasing order of atomic size
iii) Newland’s law of octaves is applicable to ___________ .
- Sodium
- Magnesium
- Calcium
- Sulphur
iv) A and B are two elements having similar properties which obey the law of octave. How many elements are there in between A and B?
- 6
- 7
- 8
- 5
v) Which of the following is true regarding Newland’s Law of Octaves?
- It worked well with only lighter elements.
- It was applicable only up to calcium.
- Both are correct.
- Both are incorrect.
2. Read the following and answer any four questions from (i) to (v)
M is an element in the form of a powder. M burns in oxygen and the product obtained is soluble in water. The solution is tested with litmus.
i) If M is a metal, then the litmus will turn _____.
- Red
- Blue
- Yellow
- Orange
ii) If M is a non-metal, then the litmus will turn _____.
- Red
- Blue
- Yellow
- Orange
iii) If M is a reactive metal, then _____ will be evolved when M reacts with dilute sulphuric acid.
- Carbon dioxide gas
- Hydrogen gas
- Nitrogen gas
- Oxygen gas
iv) If M is a metal, it will form _____ oxide, which will form ______ solution with water.
- Basic, alkaline
- Acidic, acidic
- Basic, acidic
- Acidic basic
v) If M is a non-metal, it will not conduct electricity in the form of ______.
- Diamond
- Graphite
- Cesium
- Zinc
3. Read the following and answer any four questions from (i) to (v)
It is an allotrope of carbon containing clusters of 60 carbon atoms joined together to form spherical molecules. There are 60 carbon atoms in a molecule of buckminsterfullerene, so its formula is C60. The allotrope was named buckminsterfullerene after the American architect Buckminster Fuller.
(i) How many hexagons of carbon atoms are present in one molecule of Buckminster fullerene?
- 20
- 15
- 30
- 18
(ii) How many pentagons of carbon atoms are present in one molecule of Buckminster fullerene?
- 10
- 12
- 15
- 20
(iii) Which of the following molecule is called buckminsterfullerene?
- C90
- C60
- C70
- C120
(iv)Which allotrope of carbon exists as spherical molecules?
- Diamond
- Coke
- Graphite
- Fullerene
(v) Which of the following is true about C60?
- Each carbon bonded covalently to 3 other carbon atoms in a hexagonal ball like structure.
- Each carbon bonded covalently to 4 other carbon atoms in layers
- A giant lattice structure
- Pentagonal in shape
4. Read the following and answer any four questions from (i) to (v)
Metal A burns in air, on heating, to form an oxide A2O3 whereas another metal B bums in air only on strong heating to form an oxide BO. The two oxides A2O3 and BO can react with hydrochloric acid as well as sodium hydroxide solution to form the corresponding salts and water. And element E forms an oxide E2O. An aqueous solution of E2O turns red litmus paper blue.
(i) What is the nature of oxide A2O3?
- aAcidic oxide
- Basic oxide
- Amphoteric oxide
- Neutral oxide
(ii) What is the nature of oxide BO?
- Acidic oxide
- Basic oxide
- Amphoteric oxide
- Neutral oxide
(iii) Name one metal like A.
- Sulphur
- Gold
- Aluminium
- Iron
(iv)Name one metal like B.
- Sulphur
- Gold
- Zinc
- Iron
(v) State the nature of oxide element E.
- Acidic
- Basic
- Amphoteric
- Neutral
5. Read the following and answer any four questions from (i) to (v)
Sample of five metals ‘A’, ‘B’, ‘C’, ‘D’ and ‘E’ was taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Use the above table to answer the following questions about the given metals.
i) Which of them is most reactive?
- A
- B
- D
- E
ii) What would you observe if ‘B’ is added to CuSO4?
- Reddish brown depositCBSE
- Grey deposit
- Greyish silver deposit
- Black deposit
iii) Arrange ‘A’, ‘B’, ‘C’, ‘D’ and ‘E’ in the increasing order of reactivity.
- E>A>B>C>D
- E>B>A>D>C
- E>B>A>C>D
- C>D>A>E>B
iv) Container of which metal can store zinc sulphate and silver nitrate solution?
- A
- B
- C
- D
v) Which of the above solution(s) can be stored in a container made of any of these metals?
- Aluminium sulphates
- Magnesium sulphates
- Both (a) & (b)
- None of these
6. Read the following paragraph and answer the questions that follow:
The food material taken in during the process of nutrition is used in cells to provide energy for various life processes. Diverse organisms do this in different ways – some use oxygen to breakdown glucose completely into carbon dioxide and water, some use other pathways that do not involve oxygen.
i) Which three carbon molecule is formed during the breakdown of glucose?
- Lactic acid
- Glyceraldehyde
- Acetic acid
- Pyruvate
ii) The process in which pyruvate may be converted into ethanol and carbon dioxide is
- Germination
- Fermentation
- Cellular respiration
- Oxidation
iii) Breakdown of pyruvate using oxygen takes place in the
- Cytoplasm
- Stroma
- Mitochondria
- Cellular matrix
iv) The breakdown of pyruvate in the absence of oxygen producing lactic acid occurs primarily in the
- Muscle cells
- Brain cells
- Cardiac cells
- Nerve cells
v) Observe the graph and interpret which of the following is true w.r.t. rate of respiration?
- Increases with an increase in temperature
- Increases first and then decreases with an increase in temperature
- Decreases with an increase in temperature
- Decreases first and then increases with an increase in temperature
7. Read the following paragraph and answer the questions that follow:
Plants have tissues to transport water, nutrients and minerals. Xylem transports water and mineral salts from the roots up to other parts of the plant, while phloem transports sucrose and amino acids between the leaves and other parts of the plant.
(i) Which of the following processes will not occur in the absence of xylem?
- Transport of water
- Conduction of food
- Transport of minerals
- Both A and C
(ii) Transport of food by the phloem is called
- Transpiration
- Translocation
- Guttation
- Adhesion
(iii) Which of the following is not a characteristic of xylem?
- Living cells
- Lack of cytoplasm
- Impermeable to water
- Presence of lignin
(iv)In phloem transport occurs between where the substances are made i.e. ________
and where they are used or stored i.e. ________.
- Sink, source
- Source, sink
- Origin, destination
- Destination, origin
(v) ____________ is the process which involves transport of water and minerals.
- Transpiration stream
- Translocation
- Guttation
- Adhesion
8. Read the following paragraph and answer the questions that follow:
Mendel experimented on a pea plant and considered 7 main contrasting traits in the plants. In monohybrid experiment, Mendel took two pea plants of opposite traits (one short and one tall) and crossed them. He found the first generation offspring were tall and called it F1 progeny. Then he crossed F1 progeny and obtained both tall and short plants in the ratio 3:1. In a dihybrid cross experiment, Mendel considered two traits, each having two alleles. He crossed wrinkled-green seed and round-yellow seeds and observed that all the first generation progeny (F1 progeny) were round-yellow. This meant that dominant traits were the round shape and yellow colour. He then self-pollinated the F1 progeny and obtained 4 different traits wrinkled-yellow, round-yellow, wrinkled-green seeds and round-green in the ratio 9:3:3:1.
i) Which of the following was not a trait considered by Mendel for his experiments?
- Flower colour
- Pod shape
- Stem height
- Seed type
ii) What is the phenotypic ratio of the F2 progeny in a dihybrid cross?
- 3:1
- 1:2:1
- 9:3:3:1
- 3:4
iii) What is the genotypic ratio of the F2 progeny in a monohybrid cross?
- 3:1
- 1:2:1
- 9:3:3:1
- 3:4
iv) A cross between tall and dwarf plants will produce which type of plants in the F1 generation?
- Tall
- Dwarf
- Semi-dwarf
- Short
v) Because of his contribution to the field of genetics, Mendel is known as the
- Father of genetics
- Father of botany
- Father of medicine
- Father of plant physiology
9. Read the following paragraph and answer the questions that follow:
The growing size of the human population is a cause of concern for all people. The rate of birth in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body is still going on. Some degree of sexual maturation does not necessarily mean that mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.
i) Which of the following is a common sign of sexual maturation in both boys and girls?
- Development of breasts
- Growth of pubic hair
- Adam’s apple
- Broadening of hips
ii) Which of the following is an IUCD?
- Copper-T
- Diaphragm
- Oral pill
- Tubectomy
iii) Which among the following is not a sexually transmitted disease?
- Gonorrhoea
- AIDS
- Syphilis
- Cholera
iv) A couple wants to space the birth of their second child. Which of the following preventive measure could be taken by the husband?
- Oral pills
- Diaphragms
- Tubectomy
- Condoms
v) A pregnant woman visits the doctor to determine the sex of the child? Why is she denied of this testing?
- It is a complicated test.
- It may result in female foeticide.
- It is an expensive test.
- It is harmful test for the developing foetus.
10. Read the following paragraph and answer the questions that follow:
We eat various types of food which has to pass through the same digestive tract. Naturally the food has to be processed to generate particles which are small and of the same texture. The process of digestion of food in humans involves the alimentary canal and associated digestive glands.
(i) Which of the following helps in the breakdown of starch?
- Salivary amylase
- Trypsin
- Peptidase
- Chyme
(ii) What is the role of the mucus?
- Creates alkaline medium for digestion
- Movement of food along the digestive tract
- Protect the inner lining of the stomach from the action of the acid
- Breakdown of starch into sugar
(iii) Which of the following will have a longer small intestine?
- Deer
- Lion
- Tiger
- Fox
(iv) Which of the following processes would have been obstructed in the absence of villi?
- Digestion of fats
- Breakdown of lipids
- Absorption of food
- Removal of undigested food
(v) Which of the following is not processed in the small intestine?
- Pancreatic juice
- Bile
- Saliva
- Intestinal juice
11. Study the given diagram and answer the following.
A very thin and narrow beam of white light is made incident on the glass objects shown below. Comment on the nature and behaviour of the emergent beam in all the three cases.
(Given: sin 45° = 1/√2 ⁄, sin 30° = ½)
(i) There is a similarity between two of the emergent beams. Identify the two.
- (A) and (B)
- (A) and (C)
- (B) and (C)
- Insufficient data given to identify the similarity
(ii) When light enters from air to glass, the angles of the incidence and refraction in air
and glass are 45° and 30° respectively. The refractive index of the glass is
- √2
- 1/2
- 1
- 1/√2
(iii) The phenomena which takes place when the light rays emerge out in case (B)
- reflection
- refraction
- dispersion
- scattering
(iv)What is the unit of refractive index?
- °A
- cm
- degree
- no unit
(v) The ratio of sine of angle of incidence and sine of angle of refraction for particular pair of media is
- Zero
- Unity
- Constant
- None of these
12. The figure given below illustrates the ray diagram for the formation of image by a concave mirror. The position of the is beyond the centre of the curvature of the concave mirror. On basis of the given figure answer the questions given below.
i) If focal length of the concave mirror is 10 cm, the image formed will be at a distance _____________________.
- Between 10 cm and 15 cm
- Between 10 cm and 20 cm
- Beyond 20 cm
- At 20 cm
ii) In case of concave mirror, the image distance from the pole of the mirror is
- Always positive
- Always negative
- Negative or positive depending upon the position of the object
- None of these
iii) If the size of the object in the given figure is 5 cm and the magnification produced is – 0.5. The size of the image is
- – 2.5 cm
- – 0.1 cm
- 2.5 cm
- 0.1 cm
iv) A negative sign in the magnification value indicate that the image is
- Real and inverted
- Real and erect
- Virtual and erect
- Virtual and inverted
v) If the value of magnification is greater than 1 then it indicates that the image formed is
- Diminished
- The same size as that of the object
- Enlarged
- Value of magnification cannot specify whether the image is diminished or magnified
13. I n the below circuit, a nichrome wire of length 'L' is connected between points X and Y and note the ammeter reading. The experiment is performed and repeated by inserting another nichrome wire of same thickness but twice the length i.e. ‘2L’.
i) What are the changes observed in the ammeter readings?
- Ammeter readings decreases, becomes half
- Ammeter readings increases, becomes two times
- Ammeter readings increases becomes quadrupled
- Ammeter reading decreases becomes one – fourth
ii) What change is occurred in ammeter reading if instead of changing the length the area of cross – section is doubled?
- Ammeter readings decreases, becomes half
- Ammeter readings increases, becomes two times
- Ammeter readings increases becomes quadrupled
- Ammeter reading decreases becomes one – fourth
iii) If the resistors of 5 ohms and 10 ohms are connected in series in the above circuit. What is the ratio of the current passing through the two resistors?
- 2:1
- 3:1
- 1:2
- 1:1
iv) If the resistors are connected in parallel
- Current across each resistor is same and voltage changes
- Current and voltage across each resistor is same
- Current across each resistor varies and voltage remains same
- Current changes, voltage changes
v) SI unit of current is denoted as
- A
- C
- I
- J
14. Shama has a set of five substances. She has a chart stating resistivities of all the substances.
Observe the table
She has to choose an appropriate substance for performing electrical tasks. Which of the above substance according to you –
i) Can be used as an insulator
- A
- B
- B as well as C
- E
ii) Can be used for domestic wiring
- A
- B
- A as well as C
- D
iii) Can be utilised in making solar cells and transistors
- A
- B
- C
- D
iv) Is an alloy
- A
- B
- C
- E
v) Behaves as a semiconductor
- A
- D
- C
- E
15. Ruchi fixes a sheet of white cardboard sheet on a drawing board. She places a bar magnet in the centre of it. She sprinkles iron fillings uniformly around the bar magnet. Then she taps the board gently and observes that the iron fillings arrange themselves in particular pattern.
(i) What does the pattern shape look like?
- Straight lines
- Squares
- Closed curves
- Parallel lines
(ii) Why do iron fillings arrange in a pattern?
- Due to poles of magnet
- Due to force exerted by magnet within its magnetic field
- Due to repulsion between the poles and filings
- None of the above
(iii) What do the lines along which iron filings align represent?
- Magnetic field lines
- Magnetic force
- Magnetic induction
- Magnetic susceptibility
(iv) What does the crowding of iron filings at the end of the magnet indicate?
- Magnetic field is weak at poles and stronger at middle
- Magnetic field is stronger at poles and weak at middle
- Magnetic field strength goes on decreasing from north to south pole
- Magnetic field strength goes on decreasing from south to north pole
(v) How the strength of magnetic field is indicated?
- Magnetic field strength cannot be indicated by magnetic field lines
- Far the magnetic field lines more is the magnetic strength
- Closer the magnetic field lines less are the magnetic field strength
- Closer the magnetic field lines more is the magnetic strength
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