1. Why can a small needle float on the surface of water when placed carefully?
A.
Because water has surface tension
B.
Because the needle has no weight
C.
Because water has no density
D.
Because gravity does not act on the needle
Correct Answer:
Because water has surface tension
Explanation:
The surface tension of water provides an upward force along the surface, which can support a carefully placed small needle.
2. Why can water striders walk on the surface of water?
A.
Their legs produce water
B.
Surface tension supports their weight
C.
They are heavier than water
D.
Water has no intermolecular attraction
Correct Answer:
Surface tension supports their weight
Explanation:
Water surface tension makes the surface behave like a stretched film that can support the light bodies of water striders.
3. Why does soap help in cleaning clothes?
A.
It increases the surface tension of water
B.
It decreases the surface tension of water
C.
It removes gravity from water
D.
It changes water into a gas
Correct Answer:
It decreases the surface tension of water
Explanation:
Soap lowers the surface tension of water, allowing it to spread and penetrate more easily into the fibres of clothes.
4. Why does water rise through a narrow glass tube?
A.
Due to capillary action
B.
Due to evaporation only
C.
Due to the absence of gravity
D.
Due to the expansion of the tube
Correct Answer:
Due to capillary action
Explanation:
Capillary action, caused by surface tension and adhesive forces, makes water rise in a narrow tube.
5. Which phenomenon helps water move from the roots to the upper parts of a plant?
A.
Capillary action in narrow vessels
B.
Reflection of light
C.
Conduction of heat
D.
Magnetic attraction
Correct Answer:
Capillary action in narrow vessels
Explanation:
Surface tension contributes to capillary action, helping water rise through the narrow vessels present in plants.
6. Why does ink spread through blotting paper?
A.
Because of capillary action
B.
Because the paper repels ink completely
C.
Because ink has no surface tension
D.
Because the paper produces ink
Correct Answer:
Because of capillary action
Explanation:
The tiny spaces between the fibres of blotting paper act as capillaries, drawing ink into the paper through surface tension effects.
7. Why are antiseptic liquids made to spread easily over wounds?
A.
Their surface tension is reduced
B.
Their density is made zero
C.
Their temperature is always increased greatly
D.
Their gravitational force is removed
Correct Answer:
Their surface tension is reduced
Explanation:
A liquid with lower surface tension spreads more easily over a surface, allowing an antiseptic to cover a wound effectively.
8. Why does kerosene rise through the wick of a lamp?
A.
Due to capillary action
B.
Due to the large size of the wick
C.
Due to the absence of surface tension
D.
Due to magnetic force
Correct Answer:
Due to capillary action
Explanation:
The small pores in the wick act as capillaries, and surface tension helps kerosene rise through them to the flame.
9. Why does water form nearly spherical drops on a waxed surface?
A.
Surface tension tends to minimize the surface area
B.
Water has no mass
C.
Wax increases the weight of water
D.
Gravity changes the shape of water into a sphere
Correct Answer:
Surface tension tends to minimize the surface area
Explanation:
Surface tension pulls the water molecules together and tends to reduce the exposed surface area, making a small drop nearly spherical.
10. What is the main effect of adding detergent to water while washing?
A.
It makes water spread more easily over the dirt
B.
It prevents water from touching the cloth
C.
It increases the surface tension greatly
D.
It changes water into oil
Correct Answer:
It makes water spread more easily over the dirt
Explanation:
Detergent lowers the surface tension of water, so water spreads over and wets the dirty surface more effectively.
Short questions are currently unavailable for this page.