## 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_{M}satisfies**

*X*< 0.5_{M}*X*= 0.5_{M}- 0.5 <
*X*< 0.64_{M} *X*≥ 0.64_{M}

**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
- 8
- 4
- 2

**Answer : 3**

**Question 3 : Pick out the wrong statement.**

- Heat capacity of a diatomic gas is higher than that of a monoatomic gas.
- Equal volumes of Argon and Krypton contain equal number of atoms.
- Total number of molecules contained in 22.4 litres of hydrogen at NTP is 6.023 x 10
^{23}. - 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/cm ^{2} is not equal to**

- 1 torr
- 1 bar
- 10000 mm wc
- 100 KPa = 100 000 N/m
^{2}

**Answer : 1**

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

- measures the elevation in boiling point.
- is not dependent on the temperature.
- is a function of the liquid phase composition.
- 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**

- temperature.
- volume of solution.
- moles of non-volatile solute.
- none of these.

**Answer : 1**

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

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

**Answer : 3**

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

- Conversion of graphite to diamond
- Decomposition of water
- Dehydrogenation of ethane to ethylene
- none of these

**Answer : 4**

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

- heat of solvation.
- heat of hydration.
- standard integral heat of solution.
- 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**

- 2
- 1
- 0.5
- 0.5

**Answer : 3**

**Question 11 : Average molecular weight of air is about**

- 21
- 29
- 23
- 79

**Answer : 2**

**Question 12 : 6 gms of magnesium (atomic weight = 24), reacts with excess of an acid, the amount of H _{2}produced will be __________ gm.**

- 0.5
- 1
- 3
- 5

**Answer : 1**

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

- 1 kcal/kg = 1.8 BTU/lb = 4.186 kJ/kg.
- 1 BTU/ft
^{3}= 8.9 kcal/m^{3}= 0.038 MJ/m^{3}. - 1 BTU/lb = 2.3 kcal/kg.
- 1 kcal/m
^{3}= 0.1124 BTU/ft^{3}.

**Answer : 1**

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

- molality
- mole fraction
- weight percent
- molarity

**Answer : 4**

**Question 15 : S.T.P. corresponds to**

- 1 atm. absolute pressure & 15.5°C
- 760 mm Hg gauge pressure & 15.5°C
- 760 torr & 0°C.
- 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**

- increases
- decreases
- remains unchanged
- decreases linearly

**Answer : 1**

**Question 17 : Pick out the wrong statement.**

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

**Answer : 1**

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

- 0.1013
- 1.013
- 10.13
- 101.3

**Answer : 2**

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

- 6
- 8
- 10
- 12

**Answer : 2**

**Question 20 : Pick out the wrong statement.**

- The effect of pressure on heat capacity of gases at pressure above one atmosphere and above the critical temperature is negligible.
- The value of
*C*of gases increases with increase in pressure, above atmospheric pressure._{p} - The value of
*C*at critical temperature and pressure reaches infinity._{p} - 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**

- solute concentration
- temperature
- both(1) & (2)
- 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**

- same elevation in boiling point.
- different elevation in boiling point.
- elevation in boiling point in the ratio of their molecular weights.
- none of these.

**Answer : 1**

**Question 23 : N _{2} 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)**

- 80%
- 90%
- 95%
- 98%

**Answer : 2**

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

- °API = 200(G – 1)
- °API = (141.5/G) – 131.5
- °API = (140/G) – 130
- °API = 145 – (145/G)

**Answer : 2**

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

- Osmotic pressure
- Depression of freezing point
- Lowering of vapor pressure
- none of these.

**Answer : 4**

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

- isobars
- isotones
- isotopes
- 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.**

- 10
- 100
- 1000
- 10000

**Answer : 3**

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

- thermal conductivity.
- heat capacity.
- viscosity.
- surface tension.

**Answer : 2**

**Question 29 : Density of carbon dioxide is __________ kg/Nm ^{3}.**

- 44/22400
- 44/22.4
- 22.4/44
- none of these

**Answer : 2**

**Question 30 : Assuming that CO _{2} obeys perfect gas law, calculate the density of CO_{2} (in kg/m^{3}) at 263°C and 2 atm**

- 1
- 2
- 3
- 4

**Answer : 2**

**Question 31 : One micron is equal to**

- 10
^{-4}mm - 10
^{-4}cm - 10
^{-6}m - 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**

- 10.73 kJ
- 16.15 kJ
- 18.11 kJ
- 18.33 kJ

**Answer : 3**

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

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

**Answer : 1**

**Question 34 : Equal masses of CH _{4} and H_{2} are mixed in an empty container. The partial pressure of hydrogen in this container expressed as the fraction of total pressure is**

- 1/9
- 8/9
- 1/2
- 5/9

**Answer : 2**

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

- 0
- ∞
- 1
- none of these

**Answer : 2**

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

- 6
- 1
- 7
- 10

**Answer : 1**

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

- its atomic number.
- the number of protons or electrons present in it.
- the number of neutrons present in it.
- none of these.

**Answer : 3**

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

- formation
- solution
- combustion
- fusion

**Answer : 1**

**Question 39 : A sample of well water contains 140 gm/m ^{3} Ca^{2+} ions and 345 gm/m^{3} Na^{+ }ions. The hardness of the sample of water, expressed in terms of equivalent CaCO_{3} in gm/m^{3} is (assuming atomic masses of Ca :40, Na : 23, C : 12, O : 16)**

- 350
- 485
- 140
- 345

**Answer : 1**

**Question 40 : One Newton is equal to __________ dynes.**

- 10
^{2} - 10
^{3} - 10
^{4} - 10
^{5}

**Answer : 4**

**Question 41 : A very dilute solution is prepared by dissolving ‘x _{1}‘ mole of solute in ‘x_{2}‘ mole of a solvent. The mole fraction of solute is approximately equal to**

- x
_{1}/x_{2} - x
_{2}/x_{1} - 1 – (x
_{1}/x_{2}) - 1/x
_{2}

**Answer : 1**

**Question 42 : An ideal gas can be liquified, because**

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

**Answer : 3**

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

- accumulation
- production
- input
- 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**

- atomic weight of the metal is 4.
- equivalent weight of the metal is 4.
- atomic weight of the metal is 2.
- equivalent weight of the metal is 8.

**Answer : 2**

**Question 44 : CaCO _{3} contains __________ percent of Ca by weight.**

- 40
- 48
- 96
- 12

**Answer : 1**

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

- ideal
- saturated
- supersaturated
- azeotropic

**Answer : 4**

**Question 46 : Gases having same reduced temperatures and reduced pressures**

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

**Answer : 3**

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

- Torr
- Newton/m
^{2} - Parsec
- Ata, bar or pascal

**Answer : 3**