Boiling Point

Question 1

On increasing the temperature of a liquid, its vapour pressure ____________
a) Decreases
b) Remain constant
c) Increases
d) None of the mentioned

Answer 1

c) Increases

Question 2

The boiling point of a liquid is the temperature at which the vapour pressure ____________
a) Is equal to the internal pressure
b) Is equal to the external pressure
c) Is greater than an internal pressure
d) Is lesser than an internal pressure

Answer 2

b) Is equal to the external pressure

Question 3

The normal boiling point of a liquid is the temperature at which it boils when the external pressure is ____________
a) 1 atm
b) 2 atm
c) 3 atm
d) 5 atm

Answer 3

a) 1 atm

Question 4

4. If the non-volatile impurities contaminate the liquid, its boiling point gets
   a) Depressed
   b) Elevated
   c) Remains same
   d) None of the mentioned

Answer 4

b) Elevated

Question 5

The energy required to vaporize 1 mole of a liquid is known as ____________
a) Molar heat of fusion
b) Molar heat of freezing
c) Molar heat of boiling
d) Molar heat of vaporization

Answer 5

d) Molar heat of vaporization

Question 6

At 1 atm pressure, the boiling point of water is ____________
a) 0 degC
b) 100 degC
c) -100 degC
d) None of the mentioned

Answer 6

b) 100 degC

Question 7

The boiling point and molar heat of vaporisation is dependent on ____________
a) Strength of the inter-molecular forces
b) Composition of the liquid compound
c) Size of the molecules
d) All of the mentioned

Answer 7

a) Strength of the inter-molecular forces

Question 8

Select the incorrect statement from the following options.
a) Methane and argon have weak dispersion forces so their boiling point is low
b) Diethyl ether has a dipole moment, and the dipole-dipole forces accounts for its moderately high boiling point
c) Water and ethanol have strong hydrogen bonding and hence they possess high boiling point
d) Mercury has weak metallic bonding which is responsible for its low boiling point

Answer 8

d) Mercury has weak metallic bonding which is responsible for its low boiling point

Question 9

For a given substance, choose the correct statement.
a) ΔHfus is greater than ΔHvap
b) ΔHfus is equal to ΔHvap
c) ΔHfus is smaller than ΔHvap
d) None of the mentioned

Answer 9

c) ΔHfus is smaller than ΔHvap

Question 10

The molar heat of vaporisation (ΔHvap) for water is ____________
a) 40.79 kJ/mol
b) 31.0 kJ/mol
c) 59.0 kJ/mol
d) 9.2 kJ/mol

Answer 10

a) 40.79 kJ/mol