Consider the following statements:

If there were no phenomenon of capillarity

1. It would be difficult to use a kerosene lamp
2. One would not be able to use a straw to consume a soft drink
3. The blotting paper would paper would fail to function
4. The big trees that we see around would not have grown on the earth

Which of the following statements given above are correct?

[UPSC Civil Services Exam – 2012 Prelims]

(a) 1, 2 and 3 only

(b) 1, 3 and 4 only

(c) 2 and 4 only

(d) 1, 2, 3 and 4

Answer: (b)        

Explanation:

Capillarity – The tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension.

• The threads in the wick of a lamp cause the oil to rise due to capillary action. This statement is true.
• Using a straw to drink a soft drink does not involve capillary action because additional pressure from the mouth is applied. Therefore, this statement is false.
• Blotting paper absorbs ink through the capillary action of its pores. This statement is true.
• Plants draw water from the soil through capillary action in the root-hairs. This statement is true.