An airplane of a total wing area of 120 ${\mathrm{m}}^2$ is in a level flight at some height. If the pressure difference between the upper and lower surface is 2.5 kPa, then the mass of the airplane is: [Take g = 10 ${\mathrm{ms}}^{-2}$]

1.  $2 \mathrm{x} {10}^3 \mathrm{kg}$

2.  $3 \mathrm{x} {10}^4 \mathrm{kg}$

3.  $5 \mathrm{x} {10}^4 \mathrm{kg}$

4.  $7 \mathrm{x} {10}^7 \mathrm{kg}$ 

From the adjacent figure, the correct observation is:
              
1. Pressure at the bottom of the tank (a) is greater than at the bottom of the tank (b).
2. Pressure at the bottom of the tank (a) is lesser than at the bottom of (b).
3. Pressure depends upon the shape of the container.
4. Pressure at the bottom of (a) and (b) are the same.

A liquid is poured into three vessels of the same base area and equal heights as shown in the figure, then:
                                  
1. Maximum force on the base will be for vessel C

2. Maximum force on the base will be for vessel B

3. Maximum force on the base will be for vessel A

4. Force on the base will be equal for all the vessels

A diver is 10 m below the surface of water. The approximate pressure experienced by the diver is-

1. 10⁵ Pa                   

2.  2 $\times$ 10⁵ Pa

3.  3 $\times$ 10⁵ Pa       

4.  4 $\times$10⁵ Pa

If pressure at half the depth of a lake is equal to 2/3^rd the pressure at the bottom of the lake, then the depth of the lake is:
1. 10m                 
2. 20m
3. 60m                 
4. 30m

The area of cross-section of the wider tube shown in the figure is $800 {\mathrm{cm}}^2.$ If a mass of 12 kg is placed on the massless piston, then the difference in heights h of the levels of water in the two tubes will be:

1.  10 cm

2.  6 cm

3.  15 cm

4.  2 cm

The value of g at a place decreases by 2%. Then, the barometric height of mercury:

1. increases by 2%.

2. decreases by 2%.

3. remains unchanged.

4. sometimes increases and sometimes decreases.
 

The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. The 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

A siphon in use is demonstrated in the following figure. The density of the liquid flowing in the 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 

A vertical U-tube of uniform inner cross section, contains mercury in both its arms. A glycerin (density = 1.3 g/${\mathrm{cm}}^3$) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm/${\mathrm{cm}}^3$ is poured into the other arm until the upper surfaces of the oil and glycerin are at the same horizontal level. Find the length of the oil column. [Density of mercury = 13.6 g/${\mathrm{cm}}^3$]  
                       
1. 10.4 cm
2. 8.2 cm
3. 7.2 cm
4. 9.6 cm