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Fri August 01, 2014  

Ans: Dear om.smaran.mohapatra@gmail.com

Thanks for asking us a question in Ask the Expert section of TopperLearning.com.
We cannot entertain more than 5 questions in a subject per day. In case of multiple questions within a query, please post each question individually and let us know where you are getting stuck so that we would be able to explain things better.   However, answer to your first query is,   1. The reaction is given as: Na 2 CO 3  → Na 2 O + CO 2  

Therefore, 1 mole of Na 2 CO 3  gives = 1 mole of CO 2  
​
That is, 105.98 g of Na 2 CO 3  gives = 44g of CO 2  

​9.85 g of Na 2 CO 3 ​gives = 44105.98 × 9.85 g                                    = 4.0894 g of CO 2  
​
Therefore,
Number of moles of CO 2  produced  = Mass/Molar mass                                                    = 4.0894/44                                                    = 0.0929 moles

1 mole of CO 2 gas = 22.4 L
0.0929 moles of gas At STP = 22.4 × 0.0929 L                                         =  2.0809 L of CO 2 ​ would be obtained. Regards

Topperlearning Team.

Fri August 01, 2014  

Ans: Two reactions occur here are the thermal decomposition of KClO₃ and the subsequent oxidation of Aluminum to form Alâ‚‚O₃. The two reactions are as follows:  
2 KClO₃ → 2 KCl + 3 Oâ‚‚ and 4 Al + 3 Oâ‚‚ → 2 Alâ‚‚O₃  

 When 1 mole KClO₃ is decomposed, 1.5 moles of Oâ‚‚ is produced -------> 1 mol KClO₃ x ( 3 mol Oâ‚‚ / 2 mol KClO₃) = 1.5 mol Oâ‚‚  

3 moles of oxygen produces 2 moles of aluminum oxide. As we have 1.5 moles of oxygen (half of the three needed) we can expect to produce half of the 2 moles or 1 mole aluminum oxide.
1.5 mol O₂ x ( 2 mol Al₂O₃ / 3 mol O₂) = 1 mol Al₂O₃ Thus 1 mol of Al 2 O 3 is produced.

Fri August 01, 2014  

Ans: 5 M solution means 5 moles of solute dissolved in 1 liter solvent. 5 m solution means 5 moles of solute dissolved in 1 kg solvent.

Fri August 01, 2014  

Ans: A force that involves contact with another object and which produces a change in state of rest or motion is called mechanical force.   Example: Closing the door of the house. When we want to close the door, we first make contact with the door and the initial state of rest of the door is changed and it moves so that one can close it.

Thu July 31, 2014  

Ans: Complementary angles means sum of angles is 90 o . Supplementary angles means sum of angles is 180 o .   For Example, (i) Consider triangle ABC, sum of angles of a triangle is supplementary.  (ii) Consider right angled triangle ABC with right angle at B. Sum of angles at A and C is said to be complementary.

Thu July 31, 2014  

Ans: An organelle is a subcellular structure that has a specific function. The activities of cells depends on the activities of subcellular structures within the cell (subcellular structures include organelles, the plasma membrane).

Thu July 31, 2014  

Ans: If x- t graph is a straight line parallel to x- axis, it indicates that the position of the body does not change with time which implies that the body is at rest. So  When x-t graph is a straight line parallel to x-axis then the body is at rest.

Thu July 31, 2014  

Ans: PROKARYOTIC CELL FEATURE EUKARYOTIC CELL Absence of well-defined nucleus Nucleus Presence of well-defined nucleus with a nuclear membrane Absent Nucleolus Present Presence of a single length of only DNA  Genetic material Presence of several lengths of DNA wound around certain proteins Presence of smaller ribosomes Ribosomes Presence of larger ribosomes Absence of other cell organelles Cell organelles Presence of several other cell organelles such as mitochondria, endoplasmic reticulum, chloroplasts etc. Cell division occurs by fission or budding but not by mitosis Cell division Cell division occurs by mitosis or meiosis Bacteria, blue-green algae Examples Euglena , Amoeba , plants, animals

Thu July 31, 2014  

Ans: The North Pole of a magnet is not stronger than the South Pole. Both the poles have equal strength. This strength is given as the pole strength (m) of a pole of magnet.   Earth is a giant magnet with its South Pole aligned towards the geographic North and North Pole aligned towards the geographic South. Hence, when a magnet is suspended its North Pole gets attracted towards the South (or geographic North) and its South Pole gets attracted towards the North (or geographic South).

Thu July 31, 2014  

Ans: 1.Biogas is cheaper than most common fuels especially to farmers. 2.It is a renewable source of energy as agricultural and animal wastes are used as the feed material in biogas plants.Which in turn serves as a safe and efficient method of waste disposal besides supplying energy and manure for farmers .For farmers biogas is a steady source of energy. 3.Biogas can be used as fuel for cooking.The heat produced on burning biogas in a gas stove can be used for cooking food and other domestic purposes.It thus acts as a good domestic fuel. 4. The spent dung left in the biogas plant is rich in nitrogen and phosphorus compounds which can be used as manure by the farmer.  Due to all these facts biogas is a boon to farmers.

Thu July 31, 2014  

Ans: Molarity is moles of solute per unit volume of solution and volume changes with change in temperature. As the temperature increases volume increases and molarity decreases. In other words molarity is inversely proportional to the temperature.

Thu July 31, 2014  

Ans: G i v e n space t w o space f u n c t i o n s space a r e F left parenthesis x right parenthesis equals square root of x squared minus 16 end root F left parenthesis x right parenthesis equals fraction numerator 1 over denominator square root of 49 minus x squared end root end fraction rightwards double arrow square root of x squared minus 16 end root equals fraction numerator 1 over denominator square root of 49 minus x squared end root end fraction s q u a r i n g space o n space b o t h space s i d e s space a n d space c r o s s space m u l t i p l y i n g space b o t h space o f space t h e m space g i v e s open parentheses x squared minus 16 close parentheses open parentheses 49 minus x squared close parentheses equals 1 49 x squared minus x to the power of 4 minus 16 cross times 49 plus 16 x squared equals 1 65 x squared minus x to the power of 4 minus 784 equals 1 x to the power of 4 minus 65 x squared plus 785 equals 0  x squared equals fraction numerator minus b plus-or-minus square root of b squared minus 4 a c end root over denominator 2 a end fraction x squared equals fraction numerator 65 plus-or-minus square root of 1085 over denominator 2 end fraction equals fraction numerator 65 plus-or-minus 32.94 over denominator 2 end fraction x squared equals fraction numerator 65 plus 32.94 over denominator 2 end fraction comma space x squared equals fraction numerator 65 minus 32.94 over denominator 2 end fraction x equals plus-or-minus 6.998 comma space plus-or-minus 4.004

Thu July 31, 2014  

Ans: w e space k n o w space t h a t space e to the power of i t end exponent equals cos space t space plus thin space i space sin space t i equals e to the power of i straight pi over 2 end exponent rightwards double arrow i to the power of i equals open square brackets e to the power of i straight pi over 2 end exponent close square brackets to the power of i equals e to the power of i cross times i straight pi over 2 end exponent equals e to the power of i squared straight pi over 2 end exponent equals e to the power of minus straight pi over 2 end exponent  therefore space i to the power of i equals e to the power of minus straight pi over 2 end exponent

Thu July 31, 2014  

Ans: There are 6 types of salts: 1)    Normal salts: The salts formed by the complete replacement of the replaceable hydrogen ion of an acid molecule by a basic radical. Examples: Sodium sulphate and sodium chloride               2NaOH + H 2 SO 4 → Na 2 SO 4 + 2H 2 SO 4                      HCl + NaOH →  NaCl + H 2 O 2)    Acid salts : The salts formed by partial replacement of the replaceable hydrogen ion of an acid molecule by a basic radical. Example: Sodium bisulphate NaOH + H 2 SO 4 →  NaHSO 4 + H 2 O 3)    Basic salts: The salts formed by the partial replacement of the hydroxyl group of a di- or tri-acidic base by an acidic radical. Example: Mg (OH) 2 + HCl → Mg(OH)Cl + H 2 O 4)    Double salts : The salts formed by the union of two simple salts that dissolve in water and crystallise. Example: Potash alum: K 2 SO 4 . Al 2 (SO 4 ) 3 . 24H 2 O 5)    Mixed salts: Mixed salts are those salts that contain more than one basic or acidic radical. Example: Sodium potassium carbonate NaKCO 3 6)    Complex salts: Complex salts are those salts which on dissociation give one simple ion and one complex ion. Example: Na [Ag (CN) 2 ]    Na + + [Ag (CN) 2 ] − All the salts have various uses in daily life and industries.

Thu July 31, 2014  

Ans: 1. space fraction numerator 19 z minus 7 over denominator 13 z minus 7 end fraction equals 1 c r o s s space m u l t i p l y comma space w e space g e t 19 z minus 7 equals 13 z minus 7 rightwards double arrow z equals 0  2. space L e t s space a s s u m e space H a s a n space b o u g h t space apostrophe x apostrophe space m space o f space s h i r t space m a t e r i a l comma space s o space h e space s h o u l d space h a v e space b o u g h t space fraction numerator 2 x over denominator 3 end fraction m space o f space t r o u s e r space m a t e r i a l. space T o t a l space cos t space i n c u r r e d space b y space H a s a n space i s space 50 x plus 90 cross times space fraction numerator 2 x over denominator 3 end fraction equals R s. space 110 x  H a s a n space s o l d space s h i r t space m a t e r i a l space f o r space 12 % space p r o f i t space a n d space t r o u s e r space m a t e r i a l space f o r space 10 % space p r o f i t. space S o space t o t a l space a m o u n t space H a s a n space g o t space f r o m space s a l e space i s space space 50 x open parentheses 1.12 close parentheses plus 60 x left parenthesis 1.1 right parenthesis equals R s. space 122 x space  G i v e n space t o t a l space a m o u n t space H a s a n space g o t space f r o m space s a l e space i s space R s. space 36 comma 600 rightwards double arrow 122 x equals 36 comma 600 x equals 300 A m o u n t space o f space t r o u s e r space m a t e r i a l space b o u g h t space b y space H a s a n space i s space fraction numerator 2 x over denominator 3 end fraction equals 200 m   3. space K i t e : rightwards arrow Diagonals space intersect space at space right space angles rightwards arrow Angles space between space unequal space sides space are space equal rightwards arrow 1 space D i a g o n a l space b i s e c t s space t h e space o p p o s i t e space a n g l e s rightwards arrow 1 space p a i r space o f space o p p o s i t e space a n g l e s space a r e space c o n g r u e n t  R h o m b u s : rightwards arrow A l l space p r o p e r t i e s space o f space P a r a l l e log r a m space a r e space a p p l i c a b l e space t o space R h o m b u s rightwards arrow A l l space p r o p e r t i e s space o f space K i t e space a r e space a p p l i c a b l e space t o space R h o m b u s rightwards arrow D i a g o n a l s space b i s e c t s space t h e space a n g l e s space a n d space t h e y space p e r p e n d i c u l a r l y space b i s e c t space e a c h space o t h e r rightwards arrow D i a g o n a l s space s p l i t space t h e space R h o m b u s space i n t o space 4 space c o n g r u e n t space r i g h t space a n g l e d space t r i a n g l e s  A space K i t e space c a n space b e c o m e space a space R h o m b u s space i n space t h e space s p e c i a l space c a s e space w h e r e space a l l space 4 space s i d e s space a r e space o f space s a m e space l e n g t h. space

Thu July 31, 2014  

Ans: Dear whitestone7587@gmail.com

Thanks for asking us a question in Ask the Expert section of TopperLearning.com.
A similar question is already been answered, please refer the already answered questions.

Regards

Topperlearning Team.

Thu July 31, 2014  

Ans: A neutron is made up of two down quark and one up quark so net charge will be (-1/3 e) + (-1/3e) + (+2/3e) = (-2/3 e) +(+ 2/3e) = o which indicates that neutron is nuetral.no charge as such.

Thu July 31, 2014  

Ans: Dear whitestone7587@gmail.com

Thanks for asking us a question in Ask the Expert section of TopperLearning.com.
Same question is already been answered, please refer the already answered questions.

Regards

Topperlearning Team.

Wed July 30, 2014  

Ans: Quarks are the fundamental constituent of matter and are the elementary entities(particles) that make up the subatomic particles like protons and neutrons.The quarks are assigned fractional electric charges of - 1/3 e (called the down quark, denoted by d) and + 2/3 e (called up quark, denoted by u).The proton is composed of three quarks(i.e.uud), two with charges of +2/3 e and one with charge of -1/3 e, which adds up to a net charge of + e .A neutron is made up of two down quarks and one up quark(ddu). Till now no isolated quark has been observed due to the exceptionally strong force called color force which prevents them from escaping.This force increses with seperation distance.

Wed July 30, 2014  

Ans:
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