A water film is formed between the two straight parallel wires, each of length \(10~\text{cm}\), kept at a separation of \(0.5~\text{cm}.\)Now, the separation between them is increased by \(1~\text{mm}\) without breaking the water film. The work done for this is
(surface tension of water =\(7.2\times 10^{-2}~\text{N/m}\))
1. \(7.22\times 10^{-6}~\text{J}\)
2. \(1.44\times 10^{-5}~\text{J}\)
3. \(2.88\times 10^{-5}~\text{J}\)
4. \(5.76\times 10^{-5}~\text{J}\)

A drop of mercury of radius 2 mm is split into 8 identical droplets. Find the increase in surface energy. (Surface tension of mercury is $0.465 \mathrm{J}/{\mathrm{m}}^2$) 

1. $23.4 \mathrm{\mu J}$

2. $18.5 \mathrm{\mu J}$

3. $26.8 \mathrm{\mu J}$

4. $16.8 \mathrm{\mu J}$

If two soap bubbles of equal radii r coalesce then the radius of curvature of interface between two bubbles will be

1. r                                 

2. 0

3. Infinity                         

4. 1/2r

The angle of contact between glass and mercury is

1. 0°

2. 30°

3. 90°

4. 135°

A mercury drop does not spread on a glass plate because the angle of contact between glass and mercury is

1. Acute

2. Obtuse

3. Zero

4. $90°$

The liquid meniscus in the capillary tube will be convex if the angle of contact is

1. Greater than 90°

2. Less than 90°

3. Equal to 90°

4. Equal to 0°

The value of contact angle for kerosene with a solid surface.

1. 0°

2. 90°

3. 45°

4. 33° 

Nature of meniscus for liquid of $0^0$ angle of contact

1. Plane

2. Parabolic

3. Semi-spherical

4. Cylindrical

A liquid wets a solid completely. The meniscus of the liquid in a sufficiently long tube is 

1. Flat

2. Concave

3. Convex

4. Cylindrical

For which of the two pairs, the angle of contact is same

1. Water and glass; glass and mercury

2. Pure water and glass; glass and alcohol

3. Silver and water; mercury and glass

4. Silver and chromium; water and chromium