!: (a) 20 cm: 80

10. Some mercury is poured into a capillary tube of

uniform bore and one end closed. When the tube

is held horizontally, mercury column has a length

of 4 cm and air enclosed in the closed end has a

length of 10 cm. If the tube is now held vertically,

with open end upwards, the length of the air

column will be (take atmospheric pressure at the

Tale place of experiment to be 760 mm)

(a) 10.5 cm . (6) 8.5 cm ",JI

(c) 9.0 cm mati (d) 9.5 cm 0

THE LENGTH OF THE AIR COLUMN IS 9.5 CM

Explanation:

Taking the atmospheric pressure to be 760 mmHg;

When the capillary tube is held horizontally, the pressure of the tube is 760 mmHg

when the capillary tube is held vertically, the pressure increases by 4 cm = 40 mm

The new pressure of the tube is hence, 760 + 40 mmHg = 800 mmHg

Using the pressure forlmula;

P1 V1 = P2 V2

P1 A1 L1 = P2 A2 L2

where A1 and A2 is the area of the capillary tube and it is equal, it cancels out.

P1 l1 = P2 l2

l2 = P1 l1 / P2

l2 = 760 * 10 / 800

l2 = 9.5 cm

The length of the air in the tube is 9.5 cm.

for points guys

c, liquids evaporate, creating a gas