Chapter 3 : Elements, Compounds and Mixtures - Frank Solutions for Class 9 Chemistry ICSE
Chapter - Exercise
Chapter 3 - Elements, Compounds and Mixtures Exercise 41
(a) The most abundant element present in the Earth's crust.
(b) The three most common elements present in the human body.
(c) Two elements that exist in the liquid state.
(d) One gaseous element which is
(e) Two metallic elements that can exist as liquids at about 30oC.
(f) Name two noble gases?
(b) Carbon, hydrogen, Oxygen
(c) Mercury, Bromine
(d) (i) Helium
(f) Two noble gases are-
Chapter 3 - Elements, Compounds and Mixtures Exercise 42
(i) The composition of air is not fixed i.e. the components may be present in any proportion by mass.
(ii) Components of air i.e. nitrogen, oxygen etc. do not react with each other.
Mixtures - Air, petrol, ink, gunpowder
Compounds - Common salt, alcohol, sand
A pure substance is one which is made up of only one kind of particles. These particles may be atoms or molecules.
They are mixtures of two or more chemically different substances mixed in indefinite proportions. The constituent substances retain their properties in the mixture.
Example-Mixture of salt and sand, gunpowder
(i) Copper is malleable and ductile while sulphur is neither malleable nor ductile.
(ii) Copper is a good conductor of heat while sulphur is not good conductor of heat.
Ex - Arsenic, antimony
(a) A metal stored in kerosene oil.
(b) A liquid non-metal.
(c) A metalloid
(d) A radioactive noble gas.
(e) A liquid metal
(f) A solvent for rust
(g) A gas which is highly soluble in water.
(f) Oxalic acid
(g) Carbon dioxide
(a) Elements cannot be broken into ______ by chemical or physical methods.
(b) An element is a pure substance in which the ______ number of each atom is same.
(c) Carbon is an element because the atomic number of each carbon atom is ______.
(d) An example of a homogeneous mixture of a liquid and a solid is ______.
(e) The atomicity of Oxygen is ______.
(d) mixture of salt and water
(a) A molecule
(b) Atomicity - Atomicity of an element is defined as the number of atoms present in one molecule of that element.
(a) By all living things.
(b) In the construction of buildings.
(c) As a food.
(c) Milk Sugar solution
(b) Graphite, Iodine
Chapter 3 - Elements, Compounds and Mixtures Exercise 43
(a) Chromatography: State three advantages of chromatography.
(b) Filtration: Give example of a mixture in which the components can be separated by this technique.
(c) Fractional distillation : Can a mixture of chloroform and water be separated by this method.
(d) Centrifugation: State one application of this method.
Advantages of chromatography -
(i) It requires a very small amount of the substance or sample.
(ii) The components retain their individuality during the process.
(iii) Chromatography finds application in easy separation of substances with similar physical and chemical properties.
(b) Filtration-It is a separation technique for separating a mixture in which one component should be solid and insoluble in the other liquid component.
Example- Barium sulphate in water.
(c) Fractional distillation -
It is a technique used to separate two liquids which dissolve in one another.The separation relies on the differences in boiling points of the two liquids.
No, mixture of chloroform and water cannot be separated by this method.
(d) Centrifugation:It is a method for separating the suspended particles of a substance from a liquid in which the mixture is rotated at a high speed in centrifuge machine.
Application - The clay particles in water (which are very fine) can be separated by centrifugation.
(d) Supernatant liquid
(b) A liquid condensed from vapour in distillation is called distillate.
(c) The liquid produced after filtering a suspension of a solid in a liquid is called filtrate.
(d) Supernatant liquid is the upper layer of fluid found after a mixture has been centrifuged.
(e) If there is a heterogeneous mixture containing an insoluble solid in a liquid, then the solid substance that settle down is called sediment.
(a) Obtain pure water from sea water?
(b) Obtain a sample of pure iodine and sodium chloride.
(b) A sample of pure iodine and sodium chloride is obtained by sublimation.
(i) Size of the constituents
(ii) Magnetic properties of constituents
(iii) Mass of the constituents
(iv) Solubility of the constituents
(v) Miscibilities of the constituents
(vi) Boiling point of the constituents
(vii) Diffusion rate of the constituents
(b) Can a mixture of chloroform (B.P.= 61oC) and carbon tetrachloride (B.P.=77OC) be satisfactorily separated by the process you use for separating the various fractions of petroleum? What modifications will you make in the apparatus for this purpose?
(b) Yes, mixture of chloroform (B.P.= 61oC) and carbon tetrachloride (B.P.=77OC) be satisfactorily separated by the process of fractional distillation which is used for separating the various fractions of petroleum.
For this purpose we will make two fractionating columns in the apparatus.
(a) Solid-solid mixtures
(b) Solid liquid mixtures
(c) Liquid-liquid mixtures
Give one example in each case.
(i) Magnetic separation method-Separation of iron ore from impurities
(ii) Gravity separation-Mixture of saw dust and sand
(iii) Solvent extraction-Mixture of sulphur and sand
(b) Solid- liquid mixtures
(i) Evaporation-Water and sodium chloride
(ii) Distillation-Iodine in chloroform
(iii) Filtration-Barium sulphate in water
(c) Liquid-liquid mixtures
(i) By separating funnel-Oil and water mixture
(ii) Distillation-Acetone and water
(iii) Fractional distillation-Ethyl alcohol and water
Principle of chromatography: The principle of chromatography is based on the difference in the extent of interaction (absorption) of various substances with a stationary phase and a mobile phase. A substance which interacts strongly with the mobile phase goes ahead of the other substance which interacts strongly with the stationary phase.
(a) increase in weight,
(b) decrease in weight,
(c) no change in weight
When exposed to air ?
(b) Decrease in weight - Sodium carbonate crystals
(c) No change in weight - Sodium chloride
(i) Oil and water
(ii) Chloroform and water
(a) decantation and filtration,
(b) filtrate and distillate
(c) fractional distillation and fractional crystallization,
(d) metal and metalloid.
Chapter 3 - Elements, Compounds and Mixtures Exercise 44
(a) A magnet is moved over 'X' and 'Y' separately.
(b) 'X' and 'Y' are treated with carbon disulphide separately.
(c) 'X' and'Y' are treated with dilute HCl separately. State the reason for the difference in the behavior of 'X' and 'Y'.
(b) When'X' is treated with carbon disulphide, sulphur dissolves but not iron. While, when'Y' is treated with carbon disulphide, iron sulphide does not dissolve but sinks to the bottom of the test tube.
(c) When 'X' is treated with dilute HCl, a colourless, odourless gas hydrogen is evolved which burns with a blue flame and is extinguished with a pop sound. While, when 'Y' is treated with dilute HCl, a colourless gas with the smell of rotten eggs is evolved which is H2S.
There is difference in the behavior of 'X' and 'Y' because 'X' is a mixture while 'Y' is a compound. The component of a mixture do not react chemically, so retain their identity in the mixture while the components of compound react chemically, so do not retain their identity in the compound.
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