Stoichiometry Questions and Answers

Multiple Choice Questions (MCQ) and Answers on Stoichiometry

Question 1 : The weight fraction of methanol in an aqueous solution is 0.64. The mole fraction of methanol X_Msatisfies

1. X_M < 0.5
2. X_M = 0.5
3. 0.5 < X_M < 0.64
4. X_M ≥ 0.64

Answer : 4

Question 2 :  On addition of 1 c.c. of dilute hydrochloric acid (1% concentration) to 80 c.c. of a buffer solution of pH = 4, the pH of the solution becomes

1. 1
2. 8
3. 4
4. 2

Answer : 3

Question 3 : Pick out the wrong statement.

1. Heat capacity of a diatomic gas is higher than that of a monoatomic gas.
2. Equal volumes of Argon and Krypton contain equal number of atoms.
3. Total number of molecules contained in 22.4 litres of hydrogen at NTP is 6.023 x 10²³.
4. The binary mixture of a particular com-positidn in both vapor and liquid state is known as an azeotropic mixture

Answer : 2

Question 4 : 1 kgf/cm² is not equal to

1. 1 torr
2. 1 bar
3. 10000 mm wc
4. 100 KPa = 100 000 N/m²

Answer : 1

Question 5 : The activity co-efficient of a solution, which accounts for the departure of liquid phase from ideal solution behaviour

1. measures the elevation in boiling point.
2. is not dependent on the temperature.
3. is a function of the liquid phase composition.
4. measures the depression in freezing point.

Answer : 3

Question 6 : Osmotic pressure of a dilute solution of a non volatile solute in a solvent obeying Raoult’s law is proportional to the

1. temperature.
2. volume of solution.
3. moles of non-volatile solute.
4. none of these.

Answer : 1

Question 7 : In case of an unsaturated vapor-gas mixture, the humid volume increases with increase in the

1. total pressure.
2. absolute humidity at a given temperature.
3. both (1) and (2).
4. neither (1) nor (2).

Answer : 3

Question 8 :  Which of the following is an exothermic reaction ?

1. Conversion of graphite to diamond
2. Decomposition of water
3. Dehydrogenation of ethane to ethylene
4. none of these

Answer : 4

Question 9 : Heat of solution in a system in which both solute and solvent are liquids is termed as

1. heat of solvation.
2. heat of hydration.
3. standard integral heat of solution.
4. heat of mixing.

Answer : 4

Question 10 : A solution is made by dissolving 1 kilo mole of solute in 2000 kg of solvent. The molality of the solution is

1. 2
2. 1
3. 0.5
4. 0.5

Answer : 3

Question 11 : Average molecular weight of air is about

1. 21
2. 29
3. 23
4. 79

Answer : 2

Question 12 : 6 gms of magnesium (atomic weight = 24), reacts with excess of an acid, the amount of H₂produced will be __________ gm.

1. 0.5
2. 1
3. 3
4. 5

Answer : 1

Question 13 : Pick out the wrong unit conversion of calorific value.

1. 1 kcal/kg = 1.8 BTU/lb = 4.186 kJ/kg.
2. 1 BTU/ft³ = 8.9 kcal/m³ = 0.038 MJ/m³.
3. 1 BTU/lb = 2.3 kcal/kg.
4. 1 kcal/m³ = 0.1124 BTU/ft³.

Answer : 1

Question 14 : Increasing the temperature of an aqueous solution will cause decrease in its

1. molality
2. mole fraction
3. weight percent
4. molarity

Answer : 4

Question 15 : S.T.P. corresponds to

1. 1 atm. absolute pressure & 15.5°C
2. 760 mm Hg gauge pressure & 15.5°C
3. 760 torr & 0°C.
4. 101.325 kPa gauge pressure & 15.5°C

Answer : 1

Question 16 : With rise in pressure, the solubility of gases in solvent, at a fixed temperature

1. increases
2. decreases
3. remains unchanged
4. decreases linearly

Answer : 1

Question 17 : Pick out the wrong statement.

1. ‘Reduced temperature’ of a substance is the ratio of its existing temperature to its critical temperature, both expressed on celsius scale.
2. ‘Reduced pressure’ is the ratio of the existing pressure of a substance to its critical pressure.
3. ‘Reduced volume’ is the ratio of the existing molal volume of a substance to its critical molal volume.
4. none of these.

Answer : 1

Question 18 : Vapor pressure of water at 100°C is about __________ bar.

1. 0.1013
2. 1.013
3. 10.13
4. 101.3

Answer : 2

Question 19 : At room temperature, the product [H⁺] [OH^–] in a solution is 10^-14 moles/litre. If, [OH^–] = 10^-6moles/litre, then the pH of the solution will be

1. 6
2. 8
3. 10
4. 12

Answer : 2

Question 20 : Pick out the wrong statement.

1. The effect of pressure on heat capacity of gases at pressure above one atmosphere and above the critical temperature is negligible.
2. The value of C_p of gases increases with increase in pressure, above atmospheric pressure.
3. The value of C_p at critical temperature and pressure reaches infinity.
4. all (1), (2), and (3).

Answer : 1

Question 21 : In case of a ternery system involving two liquid components and a solute, the ratio of the concentration of the solute in the two phases at equilibrium is called the distribution co-efficient. The distribution co-efficient depends upon the

1. solute concentration
2. temperature
3. both(1) & (2)
4. neither (1) nor (2)

Answer : 1

Question 22 : Solution made by dissolving equimolar amounts of different solutes in the same amount of a given solvent will have the

1. same elevation in boiling point.
2. different elevation in boiling point.
3. elevation in boiling point in the ratio of their molecular weights.
4. none of these.

Answer : 1

Question 23 : N₂ content in a urea sample was found to be only 42%. What is the actual urea content of the sample ? (molecular weight of urea = 60)

1. 80%
2. 90%
3. 95%
4. 98%

Answer : 2

Question 24 : Specific gravity on API scale is given by the relation(where, G = specific gravity at 15.5°C).

1. °API = 200(G – 1)
2. °API = (141.5/G) – 131.5
3. °API = (140/G) – 130
4. °API = 145 – (145/G)

Answer : 2

Question 25 : Which of the following is not a colligative property ?

1. Osmotic pressure
2. Depression of freezing point
3. Lowering of vapor pressure
4. none of these.

Answer : 4

Question 26 : toms of the same element, but of different masses are called

1. isobars
2. isotones
3. isotopes
4. none of these

Answer : 3

Question 27 : If pH value of an acidic solution is decreased from 5 to 2, then the increase in its hydrogen ion concentration is __________ times.

1. 10
2. 100
3. 1000
4. 10000

Answer : 3

Question 28 : Kopp’s rule is concerned with the calculation of

1. thermal conductivity.
2. heat capacity.
3. viscosity.
4. surface tension.

Answer : 2

Question 29 : Density of carbon dioxide is __________ kg/Nm³.

1. 44/22400
2. 44/22.4
3. 22.4/44
4. none of these

Answer : 2

Question 30 : Assuming that CO₂ obeys perfect gas law, calculate the density of CO₂ (in kg/m³) at 263°C and 2 atm

1. 1
2. 2
3. 3
4. 4

Answer : 2

Question 31 : One micron is equal to

1. 10^-4 mm
2. 10^-4 cm
3. 10^-6 m
4. both(2)&(3)

Answer : 4

Question 32 : Heat capacity of air can be approximately expressed as, C_p = 26.693 + 7.365 x10^-3 T, where, C_p is in J/mole.K and T is in K. The heat given off by 1 mole of air when cooled at atmospheric pressure from 500°C to – 100°C is

1. 10.73 kJ
2. 16.15 kJ
3. 18.11 kJ
4. 18.33 kJ

Answer : 3

Question 33 : Gases diffuse faster compared to liquids because of the reason that the liquid molecules

1. are held together by stronger inter-molecular forces.
2. move faster.
3. have no definite shape.
4. are heavier

Answer : 1

Question 34 : Equal masses of CH₄ and H₂ are mixed in an empty container. The partial pressure of hydrogen in this container expressed as the fraction of total pressure is

1. 1/9
2. 8/9
3. 1/2
4. 5/9

Answer : 2

Question 35 : Molar heat capacity of water in equilibrium with ice at constant pressure is

1. 0
2. ∞
3. 1
4. none of these

Answer : 2

Question 36 : If pH value of a solution is 8, then its pOH value will be

1. 6
2. 1
3. 7
4. 10

Answer : 1

Question 37 : The chemical nature of an element is independent of

1. its atomic number.
2. the number of protons or electrons present in it.
3. the number of neutrons present in it.
4. none of these.

Answer : 3

Question 38 : The heat change for the reaction, C(s) + 2S(s) → CS₂(l), is 104.2 kJ. It represents the heat of

1. formation
2. solution
3. combustion
4. fusion

Answer : 1

Question 39 : A sample of well water contains 140 gm/m³ Ca²⁺ ions and 345 gm/m³ Na⁺ ions. The hardness of the sample of water, expressed in terms of equivalent CaCO₃ in gm/m³ is (assuming atomic masses of Ca :40, Na : 23, C : 12, O : 16)

1. 350
2. 485
3. 140
4. 345

Answer : 1

Question 40 : One Newton is equal to __________ dynes.

1. 10²
2. 10³
3. 10⁴
4. 10⁵

Answer : 4

Question 41 :  A very dilute solution is prepared by dissolving ‘x₁‘ mole of solute in ‘x₂‘ mole of a solvent. The mole fraction of solute is approximately equal to

1. x₁/x₂
2. x₂/x₁
3. 1 – (x₁/x₂)
4. 1/x₂

Answer : 1

Question 42 : An ideal gas can be liquified, because

1. its molecular size is very small.
2. its critical temperature is more than 0°C.
3. forces operative between its molecules are negligible.
4. it gets solidified directly without becoming liquid.

Answer : 3

Question 43 : The rate of material __________ is zero in case of a steady state system.

1. accumulation
2. production
3. input
4. generation

Answer : 1

Question 44 : A metal oxide is reduced by heating it in a stream of hydrogen. After complete reduction, it is found that 3.15 gm of the oxide has yielded 1.05 gm of the metal. It may be inferred that the

1. atomic weight of the metal is 4.
2. equivalent weight of the metal is 4.
3. atomic weight of the metal is 2.
4. equivalent weight of the metal is 8.

Answer : 2

Question 44 : CaCO₃ contains __________ percent of Ca by weight.

1. 40
2. 48
3. 96
4. 12

Answer : 1

Question 45 : Solutions which distil without change in composition are called

1. ideal
2. saturated
3. supersaturated
4. azeotropic

Answer : 4

Question 46 : Gases having same reduced temperatures and reduced pressures

1. deviate from ideal gas behaviour to the same degree.
2. have nearly the same compressibility factor.
3. both (1) and (2).
4. neither (1) nor (2).

Answer : 3

Question 47 : Which of the following is not a unit of pressure ?

1. Torr
2. Newton/m²
3. Parsec
4. Ata, bar or pascal

Answer : 3