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Chemistry Assertion (A) & Reason (B) MCQ

Solutions · Gujarat Board (GSEB) STD 12 Science (GSEB - English Medium). 24 questions.

Questions

Assertion (A) & Reason (B) MCQ

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24 questions · timed · auto-graded

Question 11 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: One molal aqueous solution of urea contains 60g of urea in 1 kg of water.
Reason: Solution containing one mole of solute in 1000g solvent is called one molal solution.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:

Molecular weight of urea (NH2CONH2)

= 14 + 2 + 12 + 16 + 14 + 2 = 60

Number of moles $=\frac{\text{Weight}}{\text{Molecular weight}}=\frac{60}{60}=1$

$\text{m}=\frac{\text{No. of moles of solute}}{\text{Mass of solvent in kg }}=\frac{1\text{mol}}{1\text{kg}}=1\text{m}$

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Question 21 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.
  2. Assertion and reason both are correct statements but the reason is not a correct explanation for assertion.
  3. Assertion is a correct statement but the reason is a wrong statement.
  4. Assertion is a wrong statement but the reason is correct
Assertion: Molarity of a solution in liquid state changes with temperature.
Reason: The volume of a solution changes with change in temperature.
Answer
  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.

Explanation:

Molarity (M) represents the number of moles of the solute dissolved per litre of solution.
Since the volume of a liquid varies with changes in temperature, the volume of the solution would also change while the number of moles of solute present in it will remain the same (or unchanged). This, therefore, would affect the molarity of the solution.

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Question 31 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Sodium chloride used to clear snow on the roads.
Reason: Sodium chloride depresses the freezing point of water.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:

According to colligative property, on addition of a non-volatile solute to a volatile solvent, the freezing point of solution decreases.

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Question 41 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: The boiling point of 200mL of 1M urea solution is less than that of 200mL of 2M glucose solution.
Reason: Elevation of boiling point is directly proportional to the number of species present in the solution.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
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Question 51 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: If blood cells are placed in pure water, they swell and burst.
Reason: Due to osmosis, the movement of water molecules into the cell, dilutes the salt content.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Here, movement of water molecules takes place in highly concentrated salt content of blood cell to such an extent that the cell membrane ruptures.

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Question 61 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.
  2. Assertion and reason both are correct statements but the reason is not a correct explanation for assertion.
  3. Assertion is a correct statement but the reason is a wrong statement.
  4. Assertion is a wrong statement but the reason is correct
Assertion: Ice melts faster at high altitudes.
Reason: At high altitudes atmospheric pressure is high.
Answer
  1. Assertion is a wrong statement but the reason is correct

Explanation:

Ice melts slowly at high altitude because melting is favoured at high pressure at high altitude the atmospheric pressure is low and so the ice melts slowly

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Question 71 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: The pressure exerted by the vapour in equilibrium with a liquid at a given temperature is called its vapour pressure.
Reason: If a non-volatile solute is added to a solvent to give a solution, the vapour pressure of the solution is found to be greater than the vapour pressure of the pure solvent.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

The vapour pressure of solution is found to be lower than the vapour pressure of pure solvent. In the solution, the surface has both solute and solvent molecules, thereby the number of solvent molecules gets reduced at the surface, consequently, the number of solvent molecules escaping from the surface is correspondingly reduced and this results in the decrease in vapour pressure of the solvent

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Question 81 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: The molality of the solution does not change with change in temperature.
Reason: The molality is expressed in units of moles per 1000g of solvent.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

Molality does not depend upon volume thus, it does not depend on temperature.

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Question 91 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: The vapour pressure of a liquid decreases if some non-volatile solute is dissolved in it.
Reason: The relative lowering of vapour pressure of a solution containing a non-volatile solute is equal to the mole fraction of the solute in the solution.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

On adding a non-volatile solute in a liquid, the vapour pressure decreases because some molecules of the solvent on the surface are replaced by the molecules of the solute.

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Question 101 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Camphor is used as a solvent in the determination of molecular masses of naphthalene, anthracene, etc.
Reason: Camphor has high molal elevation constant.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

Camphor has high molal depression constant.

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Question 111 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: If a liquid solute, more volatile than the solvent, is added to the solvent, the vapour pressure of the solution may increase i.e., p(s) > pº.
Reason: In the presence of a more volatile liquid solute, only the solute will fonn the vapours and solvent will not.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

Both the solute and solvent will form the vapours but vapour phase will become richer with the more volatile component.

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Question 121 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Water boils at 373K as the vapour pressure at this temperature becomes equal to atmospheric pressure.
Reason: Vapour pressure of water is less than 1.013 bar at 373K.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

At 373K (100ºC), the vapour pressure ox water is equal to 1 atmospheric pressure which is 1.013 bar.

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Question 131 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Elevation in baiting point and depression in freezing point are colligative properties.
Reason: All colligative properties are used for the calculation of molecular masses.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

Elevation in boiling point and depression in freezing point are colligative properties because they depend only on the number of solute particles in a solution irrespective of their nature. But all colligative properties are not used for mass determination for every substance, as some give very low precision, or require excessive heating or cooling.

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Question 141 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Dilute solution of benzene and toluene is an ideal solution.
Reason: Benzene and toluene fonn H-bonding with each other.
Answer
  1. Assertion is correct statement but reason is wrong statement.

Explanation:

Benzene and toluene do not form H-bonding with each other.

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Question 151 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Solutions show deviations from Raoult's law.
Reason: The cause for these deviations lies in the nature of interactions at the molecular level.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:

On mixing two dissimilar substances, their molecular environment changes. Suppose the two components that are mixed to form a non-ideal solution are A and B.

When A - B interactions < A - A or B - B interactions, there is a positive deviation from Raoult's law.

When A - B interaction > A - A or B - B interactions, there is a negative deviation from Raoult's law.

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Question 161 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Amalgam is a homogeneous solution.
Reason: Amalgam is a solution in which mercury is solute and zinc is solvent.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

In amalgam, solute and solvent are uniformly distributed.

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Question 171 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Solutions having the same osmotic pressure are called isotonic solutions.
Reason: Ca2+ and K+ ions are responsible for maintaining proper osmotic pressure balance in the cells of organism.
Answer
  1.  Assertion is correct statement but reason is wrong statement.

Explanation:

Sodium ion, Na+ and potassium ion, K+ are responsible for maintaining proper osmotic pressure balance inside and outside of the cells of organisms. 

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Question 181 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.
  2. Assertion and reason both are correct statements but the reason is not a correct explanation for assertion.
  3. Assertion is a correct statement but the reason is a wrong statement.
  4. Assertion is a wrong statement but the reason is correct
Assertion: The addition of ethylene glycol (non–volatile) to water lowers the freezing point of water hence used as antifreeze
Reason: Heat must be removed from the water to make it freeze.
Answer
  1. Assertion is a correct statement but the reason is a wrong statement.

Explanation:

Ethylene glycol is used as antifreeze, and it is a non-volatile substance that cannot evaporate into gas under certain conditions. If a substance is non-volatile then it has a high boiling point and low vapour pressure. Ethylene glycol is miscible in water in all proportions.

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Question 191 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: When a concentrated solution is diluted by adding more water, the number of moles of solute in the solution remains unchanged.
Reason: Number of moles of a solute is equal to the product of molarity and volume of solution in litres.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

Moles of solute are equal to product of molarity and volume (i.e., Mol L-1 × L + Mol) and when we add more solvent, the volume increases but the molarity decreases correspondingly so that their product i.e., the total number of moles remains constant.

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Question 201 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Osmotic pressure is a colligative property.
Reason: Osmotic pressure depends only on the number of particles dissolved in solution.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:

A colligative property of a solution is one that depends only on the number of particles of the solute dissolved in it, rather than on the nature of the solute.

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Question 211 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: Reverse osmosis is used in the desalination of sea water.
Reason: When pressure more than osmotic pressure is applied, pure water is squeezed out of the sea water through the membrane.
Answer
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.

Explanation:

If a pressure larger than the osmotic pressure is applied to the solution side, the pure solvent flows out of the solution to the solvent through semi-permeable membrane and this phenomenon is called reverse osmosis.

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Question 221 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: A solution is a homogeneous mixture of two or more chemically non-reacting substances.
Reason: Solutions can be made between any two states of matter.
Answer
  1. Assertion and reason both are correct statements but reason is not correct explanation for assertion.

Explanation:

A homogeneous mixture consists of a single phase which has properties that may differ from those of the individual components i.e., solute and solvent.

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Question 231 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
Assertion: If more and more non-volatile solute is added to a solvent, the freezing point of the solution keeps on becoming higher and higher.
Reason: Presence of large amount of the solid solute allow the solution to freeze more rapidly.
Answer
  1. Assertion is wrong statement but reason is correct statement.

Explanation:

The freezing point keeps on becoming lower and lower. Depression in freezing point is a colligative property as it depends on the number of particles of the solute present in solution, so solution will freeze more rapidly on adding large amount of non-volatile solute.

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Question 241 Mark
In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.
  2. Assertion and reason both are correct statements but the reason is not a correct explanation for assertion.
  3. Assertion is a correct statement but the reason is a wrong statement.
  4. Assertion is a wrong statement but the reason is correct

Assertion: Molecular mass of benzoic acid when determined by colligative properties is found high.

Reason: Dimerization of benzoic acid.

Answer
  1. Assertion and reason both are correct statements but the reason is the correct explanation for assertion.

Explanation:

Colligative properties are the properties of solutions containing non-volatile solute. It is correct that the molecular mass of benzoic acid when determined by colligative properties is found abnormally high. This is because dimerisation of benzoic takes place in solution resulting in high molecular mass. Therefore, assertion and reason are true and the reason is the correct explanation.

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Assertion (A) & Reason (B) MCQ - Chemistry STD 12 Science Questions - Vidyadip