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# Multiple choice question for engineering

## Set 1

1. Amount of substance containing 6.022*10^23 entities is called
a) Mole
b) Molecular weight
c) Molar mass
d) None of the mentioned

Answer: a [Reason:] Amount of substance containing 6.022*10^23 entities is called mole.

2. Two statements are given as below
I: lb mole is composed of 453.6*6.022*1023 molecules
II: gm mole is composed of 6.022*1023 molecules
Number of correct statements is/are
a) 0
b) 1
c) 2
d) None of the mentioned

Answer: 2 [Reason:] A gm mole is composed of 6.022*10^23 molecules and 1 lb mole is 453.6 times a gm mole.

3. Molecular weight is the ratio of _______ and ________
a) Mass, Mole
b) Mole, Mass
c) Mole, Mole
d) Mass, Mass

Answer: a [Reason:] Molecular weight is the ratio of Mass and Mole.

4. How many g moles of H are there in 22 g of H2SO4?
a) 0.4489
b) 0.2245
c) 0.1256
d) 0.3256

Answer: a [Reason:] g moles of H = 2(gm moles of H2SO4).

5. How many g moles of S are there in 22 g of H2SO4?
a) 0.4489
b) 0.2245
c) 0.1256
d) 0.3256

Answer: b [Reason:] g moles of S = gm moles of H2SO4.

6. How many lb moles of O are there in 22 g of H2SO4?
a) 1.978*10-4
b) 1.978*10-3
c) 1.978*10-2
d) 1.978*10-1

Answer: b [Reason:] lb mole = 454*gm mole, lb moles of O = 4(lb moles of H2SO4).

7-8. 500 lb of N2 is there in a container
7. How many pound moles of N2 does it contain?
a) 17.86
b) 35.7
c) 0.039
d) 0.078

Answer: a [Reason:] lb moles = mass in lb/molecular weight.

8. How many gram moles of N2 does it contain?
a) 8107
b) 6789
c) 7583
d) 7357

Answer: a [Reason:] gm moles = mass in gm/molecular weight.

9. 58.5 gms of NaCl contains
a) 1 gm mole of NaCl
b) 1 lb mole of NaCl
c) Both a and b
d) Neither a nor b

Answer: a [Reason:] gm moles = mass in gm/molecular weight.

10.40 gms of NaOH contains
a) 6.022*1023 molecules
b) 1 molecule
c) 13.24*1021 molecules
d) 6.022*1021 molecules

Answer: a [Reason:] 40 gms of NaOH = 1 gm mole of NaOH = 6.022*10^23 molecules.

## Set 2

1-2. A vessel contains 4 lb of H2SO4.
1. How much pound mole of H2SO4 is there in the vessel?
a) 0.0408
b) 18.53
c) 0.0816
d) None of the mentioned

Answer: a [Reason:] lb mole = mass in lb/molecular weight.

2. How much gram mole of H2SO4 is there in the vessel?
a) 18.53
b) 0.0408
c) 18.53
d) None of the mentioned

Answer: a [Reason:] lb mole = mass in lb/molecular weight.

3. How many pounds of NaOH are in 15 g mole of NaOH?
a) 1.32
b) 2.64
c) 3.96
d) 5.28

Answer: a [Reason:] First convert 15 g mole of NaOH to grams of NaOH, and then use the conversion of 1 lb = 454g.

4. Mass of a compound per mole is _________
a) Mole
b) Molecular weight
c) Mole fraction
d) None of the mentioned

Answer: b [Reason:] Mass of a compound per mole is called Molecular weight.

5. A pseudo molecular weight computed by dividing the mass in a mixture or solution by the number of moles in the mixture or solution is called
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) None of the mentioned

Answer: b [Reason:] A pseudo molecular weight computed by dividing the mass in a mixture or solution by the number of moles in the mixture or solution is called average molecular weight.

6. The __________ of an element is the mass of an atom based on the scale that assigns a mass of exactly 12 to the carbon isotope 12C .
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) None of the mentioned

Answer: c [Reason:] The atomic weight of an element is the mass of an atom based on the scale that assigns a mass of exactly 12 to the carbon isotope 12C.

7. The molecular weight of a compound is nothing more than the sum of the weights of atoms of which it is composed.
The above given statement is
a) Correct
b) Incorrect
c) The definition should be more proper
d) None of the mentioned

Answer: a [Reason:] The molecular weight of a compound is nothing more than the sum of the weights of atoms of which it is composed.

8. How many molecules are there in 4*10-3 lb moles of carbon?
a) 12.044 *1023
b) 12.044 *1026
c) 12.044 *1029
d) 12.044 *1022

Answer: a [Reason:] 4*10-3 lb moles of C = 2 gm moles of C.

9. _____________ is the number of moles of a particular substance in a mixtures or solution divided by the total number of moles present in the mixture or solution.
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) Mole fraction

Answer: d [Reason:] Mole fraction is the number of moles of a particular substance in a mixtures or solution divided by the total number of moles present in the mixture or solution.

10. __________ is mass of a particular substance divided by the total mass of all the substances present in the mixture or solution.
a) Molecular weight
b) Weight fraction
c) Atomic weight
d) Mole fraction

Answer: b [Reason:] Weight fraction is mass of a particular substance divided by the total mass of all the substances present in the mixture or solution.

## Set 3

1-2. A vessel contains 4 lb of H2SO4.
1. How much pound mole of H2SO4 is there in the vessel?
a) 0.0408
b) 18.53
c) 0.0816
d) None of the mentioned

Answer: a [Reason:] lb mole = mass in lb/molecular weight.

2. How much gram mole of H2SO4 is there in the vessel?
a) 18.53
b) 0.0408
c) 18.53
d) None of the mentioned

Answer: a [Reason:] lb mole = mass in lb/molecular weight.

3. How many pounds of NaOH are in 15 g mole of NaOH?
a) 1.32
b) 2.64
c) 3.96
d) 5.28

Answer: a [Reason:] First convert 15 g mole of NaOH to grams of NaOH, and then use the conversion of 1 lb = 454g.

4. Mass of a compound per mole is _________
a) Mole
b) Molecular weight
c) Mole fraction
d) None of the mentioned

Answer: b [Reason:] Mass of a compound per mole is called Molecular weight.

5. A pseudo molecular weight computed by dividing the mass in a mixture or solution by the number of moles in the mixture or solution is called
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) None of the mentioned

Answer: b [Reason:] A pseudo molecular weight computed by dividing the mass in a mixture or solution by the number of moles in the mixture or solution is called average molecular weight.

6. The __________ of an element is the mass of an atom based on the scale that assigns a mass of exactly 12 to the carbon isotope 12C .
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) None of the mentioned

Answer: c [Reason:] The atomic weight of an element is the mass of an atom based on the scale that assigns a mass of exactly 12 to the carbon isotope 12C.

7. The molecular weight of a compound is nothing more than the sum of the weights of atoms of which it is composed.
The above given statement is
a) Correct
b) Incorrect
c) The definition should be more proper
d) None of the mentioned

Answer: a [Reason:] The molecular weight of a compound is nothing more than the sum of the weights of atoms of which it is composed.

8. How many molecules are there in 4*10-3 lb moles of carbon?
a) 12.044 *1023
b) 12.044 *1026
c) 12.044 *1029
d) 12.044 *1022

Answer: a [Reason:] 4*10-3 lb moles of C = 2 gm moles of C.

9. _____________ is the number of moles of a particular substance in a mixtures or solution divided by the total number of moles present in the mixture or solution.
a) Molecular weight
b) Average molecular weight
c) Atomic weight
d) Mole fraction

Answer: d [Reason:] Mole fraction is the number of moles of a particular substance in a mixtures or solution divided by the total number of moles present in the mixture or solution.

10. __________ is mass of a particular substance divided by the total mass of all the substances present in the mixture or solution.
a) Molecular weight
b) Weight fraction
c) Atomic weight
d) Mole fraction

Answer: b [Reason:] Weight fraction is mass of a particular substance divided by the total mass of all the substances present in the mixture or solution.

## Set 4

1. How many gm moles oxygen are there in 88 gms carbon di oxide?
a) 1
b) 2
c) 3
d) 4

Answer: d [Reason:] 88gms of CO2 = 2 moles of CO2 = 4 moles of oxygen.

2. What is the percent water in CuSO4.5H2O?
a) 12
b) 14
c) 16
d) 18

Answer: c [Reason:] Percentage water = mass of water in the molecule/Total mass of the molecule.

3. What is the average molecular weight of a gas containing 20% N2 (molecular wt. = 28) and 80% SO2 (molecular wt. = 64)?
a) 28.4
b) 56.8
c) 24.4
d) 48.8

Answer: b [Reason:] Take 1 gm mole of the Gas and then average molecular weight = 0.20×28+0.80×64.

4. Two statements are given as
(1) When a percentage of fractions is given for gas, it is assumed that it refers to a mole fraction
(2) When a percentage of fractions is given for liquid or solid, it is assumed that it refers to the weight fraction
True statements are
a) 1
b) 2
c) Both 1 and 2
d) Neither 1 nor 2

Answer: c [Reason:] This is a simple assumption, unless otherwise specified.

5. A bucket contains 10 kg of water and 10 kg of NaOH. The respective mass fraction of water and the mole fraction of NaOH are
a) 0.5 and 0.31
b) 1.0 and 0.62
c) 0.5 and 0.69
d) 1.0 and 0.50

Answer: a [Reason:] Mole fraction of X = moles of X/total moles and mass fraction of X = mass of X/total mass.

6. What is the formula for a solid compound that contains 42.11% C, 51.46% O, and 6.43% H and having molecular weight about 341.
a) C10 O12H29
b) C11O13 H
c) C12O11H22
d) C12O10H37

Answer: c [Reason:] Take 100 g of the compound and calculate the ratio of the molecules, then make it integer to get the chemical formula.

7. If in a compound the moles of consisting atoms are doubled then the mole fraction of a particular atom will be
a) Double
b) Half
c) Remain same
d) None of the mentioned

Answer: a [Reason:] mole fraction of X = moles of the X/total moles.

8. Select the correct statement
a) 1 mole of SO2 and 64 g of Ethyl Chloride have same number of moles
b) 1 mole of SO2 and 64 g of Ethyl Chloride don`t have same molecular weights
c) Both a and b
d) Neither a nor b

Answer: a [Reason:] 1 mole of SO2 = 64 g = 1 mole of Ethyl Chloride.

9. What is a mole?
a) A mole is found in a certain number of cm3 of one substance or another.
b) A mole is the sum of atomic weights.
c) A mole is the number of molecules in one gram of a substance.
d) None of the mentioned

Answer: d [Reason:] A mole is number of molecules.

10. What will be the molecular weight of a chemical, consisting 2 moles of H2SO4, 3 moles of SO2 and 1 mole of NaOH?
a) 128
b) 228
c) 328
d) 428

Answer: d [Reason:] Molecular weight = 2 moles of H2SO4(98)+3 moles of SO2(64)+1 mole of NaOH(40).

## Set 5

1. How many gm moles oxygen are there in 88 gms carbon di oxide?
a) 1
b) 2
c) 3
d) 4

Answer: d [Reason:] 88gms of CO2 = 2 moles of CO2 = 4 moles of oxygen.

2. What is the percent water in CuSO4.5H2O?
a) 12
b) 14
c) 16
d) 18

Answer: c [Reason:] Percentage water = mass of water in the molecule/Total mass of the molecule.

3. What is the average molecular weight of a gas containing 20% N2 (molecular wt. = 28) and 80% SO2 (molecular wt. = 64)?
a) 28.4
b) 56.8
c) 24.4
d) 48.8

Answer: b [Reason:] Take 1 gm mole of the Gas and then average molecular weight = 0.20×28+0.80×64.

4. Two statements are given as
(1) When a percentage of fractions is given for gas, it is assumed that it refers to a mole fraction
(2) When a percentage of fractions is given for liquid or solid, it is assumed that it refers to the weight fraction
True statements are
a) 1
b) 2
c) Both 1 and 2
d) Neither 1 nor 2

Answer: c [Reason:] This is a simple assumption, unless otherwise specified.

5. A bucket contains 10 kg of water and 10 kg of NaOH. The respective mass fraction of water and the mole fraction of NaOH are
a) 0.5 and 0.31
b) 1.0 and 0.62
c) 0.5 and 0.69
d) 1.0 and 0.50

Answer: a [Reason:] Mole fraction of X = moles of X/total moles and mass fraction of X = mass of X/total mass.

6. What is the formula for a solid compound that contains 42.11% C, 51.46% O, and 6.43% H and having molecular weight about 341.
a) C10 O12H29
b) C11O13 H
c) C12O11H22
d) C12O10H37

Answer: c [Reason:] Take 100 g of the compound and calculate the ratio of the molecules, then make it integer to get the chemical formula.

7. If in a compound the moles of consisting atoms are doubled then the mole fraction of a particular atom will be
a) Double
b) Half
c) Remain same
d) None of the mentioned

Answer: a [Reason:] mole fraction of X = moles of the X/total moles.

8. Select the correct statement
a) 1 mole of SO2 and 64 g of Ethyl Chloride have same number of moles
b) 1 mole of SO2 and 64 g of Ethyl Chloride don`t have same molecular weights
c) Both a and b
d) Neither a nor b

Answer: a [Reason:] 1 mole of SO2 = 64 g = 1 mole of Ethyl Chloride.

9. What is a mole?
a) A mole is found in a certain number of cm3 of one substance or another.
b) A mole is the sum of atomic weights.
c) A mole is the number of molecules in one gram of a substance.
d) None of the mentioned

Answer: d [Reason:] A mole is number of molecules.

10. What will be the molecular weight of a chemical, consisting 2 moles of H2SO4, 3 moles of SO2 and 1 mole of NaOH?
a) 128
b) 228
c) 328
d) 428