Surface Tension & Capillary Action
1. Which of the following is not a result of surface tension?
a) Nearly spherical shape of a raindrop
b) Capillary rise
c) Removal of dirt by soap or detergent
d) Flow of a liquid
Answer: d
2. A liquid drop tends to form a spherical shape due to:
a) Surface tension
b) Viscous force
c) Gravitational force
d) Elastic force
Answer: a
3. What causes a liquid drop to contract and occupy minimum surface area?
a) Surface tension
b) Vapour pressure
c) Density
d) Viscosity
Answer: a
4. When detergent is added to water, its surface tension:
a) Increases
b) Decreases
c) Remains unchanged
d) Becomes zero
Answer: b
5. Why do dirty clothes with grease or oil stains get cleaned when detergent is added to water?
a) Detergent reduces surface tension between water and oil
b) Detergent increases surface tension
c) Detergent increases water’s viscosity
d) Detergent reduces viscosity of the mixture
Answer: a
6. Materials used in raincoats and tents repel water due to:
a) Surface tension
b) Viscosity
c) Specific gravity
d) Elasticity
Answer: a
7. When both a glass tube and a capillary tube are immersed in water, the rise of water is observed in:
a) Both tubes
b) Only the glass tube
c) Only the capillary tube
d) Neither
Answer: a
Pressure, Buoyancy & Viscosity
8. The wall of a dam is made thicker at the base to:
a) Streamline water flow
b) Withstand increasing pressure with depth
c) Balance horizontal pressure
d) Resist atmospheric pressure
Answer: b
9. Which of the following liquids is the most viscous?
a) Oil
b) Milk
c) Water
d) Petrol
Answer: a
10. The upthrust experienced by two rods (one copper, one steel) is the same in water. Hence, they have:
a) Equal volume
b) Equal weight
c) Equal density
d) Equal mass
Answer: a
11. The principle behind the working of a washing machine is:
a) Dialysis
b) Diffusion
c) Reverse osmosis
d) Centrifugation
Answer: d
12. What force explains the working of hydraulic brakes in automobiles?
a) Bernoulli’s law
b) Poiseuille’s principle
c) Pascal’s law
d) Archimedes’ principle
Answer: c
Buoyancy & Fluid Displacement
13. A boat will not sink if it displaces water equal to its own:
a) Volume
b) Weight
c) Surface area
d) Density
Answer: b
14. When a stone is fully immersed in water, it displaces water equal to its:
a) Density
b) Specific gravity
c) Weight
d) Volume
Answer: c
15. Water enters the root hairs of plants due to:
a) Atmospheric pressure
b) Capillary pressure
c) Root pressure
d) Osmotic pressure
Answer: d
16. When cream is removed from milk, the density of milk:
a) Increases
b) Decreases
c) Remains the same
d) May increase or decrease
Answer: a
Mechanical Systems & Pulley
17. Why is a single fixed pulley used to draw water from a well?
a) It has 100% efficiency
b) It has low velocity ratio
c) It offers high mechanical advantage
d) It allows force to be applied in a convenient direction
Answer: d