A rectangular film of liquid is extended from \((4~\text{cm} \times2 ~\text{cm})\) to \((5 ~\text{cm}\times 4 ~\text{cm})\). If the work done is \(3 \times 10^{-4}~\text{J},\) the value of the surface tension of the liquid is: 
1. \(0.25\) N/m
2. \(0.125\) N/m
3. \(0.2\) N/m
4. \(8.0\) N/m

Water rises to a height h in capillary tube . If the length of capillary tube above the surface of water is made less than h, then

(1) water rises upto the tip of capillary tube and then starts overflowing like a fountain

(2) water rises upto the top of capillary tube and stays there without overflowing

(3) water rises upto a point a little below the top and stays there

(4) water does not rise at all

If pressure at half the depth of a lake is equal to 2/3 pressure at the bottom of the lake ,then what is the depth of the lake ?

(a) 10 m                           (b) 20 m
(c) 60 m                           (d) 30 m

Two bodies are in equilibrium when suspended in water from the arms of a balance. The mass of one body is \(36\) g and its density is \(9\) g/cm³. If the mass of the other is \(48\) g, its density in g/cm³ will be:
1. $\frac{4}{3}$                                         

2. $\frac{3}{2}$

3. \(3\)                                           

4. \(5\)

An inverted bell lying at the bottom of a lake 47.6 m deep has 50 cm³ of air trapped in it. The bell is brought to the surface of the lake. The volume of the trapped air will be (atmospheric pressure = 70 cm of Hg and density of Hg = 13.6 g/cm³) 
(1) 350 cm³                               

(2) 300 cm³

(3) 250 cm³                               

(4) 22 cm³

A siphon in use is demonstrated in the following figure. The density of the liquid flowing in siphon is 1.5 gm/cc. The pressure difference between the point P and S will be

(1) ${10}^5 \mathrm{N}/\mathrm{m}$                                 

(2) $2\times {10}^5 \mathrm{N}/\mathrm{m}$

(3) Zero                                       

(4) Infinity 

The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. Ratio of density of mercury to that of air is ${10}^4$. The height of the hill is
(1) 250 m                             

(2) 2.5 km

(3) 1.25 km                           

(4) 750 m

Equal masses of water and a liquid of relative density 2 are mixed together, then the mixture has a density of
(1) 2/3                                 

(2) 4/3

(3) 3/2                                 

(4) 3

The value of g at a place decreases by 2%. The barometric height of mercury
(1) Increases by 2%

(2) Decreases by 2%

(3) Remains unchanged

(4) Sometimes increases and sometimes decreases

A barometer kept in a stationary elevator reads 76 cm. If the elevator starts accelerating up, the reading will be
(1) Zero                                       

(2) Equal to 76 cm

(3) More than 76 cm                     

(4) Less than 76 cm