Liquids:MCQs & Answers with Explanation

1. Van Der Waal's forces are effective

a) at long distance
b) Both at long as well as short distance
c) only at short distance
d) independent of distance

... Answer is c)
Explanation: Van der Waal,s forces produce when molecules become closer to each other and exist for short interval of time. These forces only exist as long as molecules remain closer to each other. As molecules become away from each other, these forces vanish away.

2. Which one of the following forces are also called London forces?

a) Ion-dipole forces
b) Dipole-induced dipole forces
c) Dipole-dipole forces
d) Dispersion forces

... Answer is d)
Explanation: London forces are called dispersion forces as London Theory has much similarity with quantum mechanical theory of light dispersion.

3. Which of the the following two halogens are gases at room temperature

a) Fluorine and iodine
b) Chlorine and bromine
c) Fluorine and chlorine
d) Iodine and bromine

... Answer is c)
Explanation: Both Fluorine and chlorine are gases at room temperature. Reason is that among molecules of these gases, London dispersion forces are weaker due to their lesser polarizabilty and relatively smaller atomic size.

4. Intermolecular forces are of

a) Two types
b) Three types
c) Three types
d) Five types

... Answer is d)
Explanation:There are five forces which include: 1. Dipole-dipole forces, 2. dipole-induced dipole forces, 3. ion-dipole forces, 4. London dispersion forces 5. hydrogen bonding

5. Thermostate is the instrument which

a) Increases the temperature
b) Decrewases the temperature
c) Maintain the temperature
d) Fluctuate the temperature

... Answer is c)
Explanation: Thermostate is a modern word derived from two Greek words thermo (heat) and statos (same). So, from its name one can easily conclude that thermostat is something that maintains the temperature.

6. The scientist who discussed the of phenomenon of viscosity are

a) Poiseuille
b) Newton
c) Fritz
d) Vander Wall

... Answer is a)
Explanation: Poiseuille was the scientist who discussed the phenomenon of viscosity. The unit of viscosity is poi's name after his name.

7. The distillation under the reduced pressure is calld

a) fractional distillation
b) vacuum distillation
c) steam distillation
d) pressure distillation

... Answer is b)
Explanation: Distillation is a process in which a mixture of liquids is separated on the bases of their differences of their boiling points. In vacuum distillation, external pressure is reduced with the help of vacuum pump. This method is particularly useful for separation of heat sensitive liquids which are decomposed before reaching their boiling point.

8. The unit of surface tension is

a) Newton per meter
b) Newton per meter square
c) 760 mm of Hg
d) Newton Square per meter

... Answer is a)
Explanation: Surface tension is a force in Newton acting per unit length (m).

9. The intermediate phase lying between the solid phase and normal liquid phase is called

a) crystalline solid
b) liquid crystals
c) Mesogens
d) crystal lattice

... Answer is b)
Explanation: liquid crystal is a substance that flows like liquids and have some properties of solid. In simple words, it is the state of substance which exist between its solid and liquid states.

10. In which of the following are particles, the most disordered?

a) water at 100°C
b) steam at 100°C
c) impure water at 102°C
d) water at 10°C

... Answerq10 b)
Explanation: As steam is a gaseous phase of water and hence, gas molecules are more random and disordered than liquid phase of water.

11. Which of these statements best supports the idea that matter is made up of particles ?

a) Liquids always fill the space available to them
b) liquids are easily compressible
c) 1 cm³ of water produces only 1700 cm³ of steam
d) if a bottle of perfumes opened, the smell spread quickly

... Answer is d)
Explanation: If a bottle of the ether is opened, the smell is quickly detected in all parts of the room. This is the best evidence that a matter may exist as tiny particles moving randomly in all direction.

12. Which of these processes involves a weakening of the attraction between particles

a) condensation
b) freezing
c) crystallization
d) evaporation

... Answer is d)
Explanation: According to Coulomb law, forces of attraction are inversely proportional to square root of the distance between charged particle. Hence, in evaporation, moleculs are widely separated from each other, so, this process involves weakening of intermolecular forces.

13. A liquid is thought to be ethanoic acid (acetic acid), which of the following is the best way to test its purity?

a) Measure its B.P.
b) React it with ethanol
c) Burn it completely in oxygen
d) Dehydrate it with concentrated H₂SO₄

... Answer is a)
Explanation: Each organic compounds has its characteristics boiling point. So, ethanoic acid can be identified from measuring its boiling point.