If tension of sonometer wire is made four times, then its frequency will change by a factor of

• 2

• 4

• 1/2

• 6

Dancing of small pieces of camphor on the surface of water is due to

• viscosity

• surface tension

• weight

• lifting force

A ballon contains 500 m³ of He at 27°C and 1 atmospheric pressure. The volume of He at − 3°C and 0.5 atmospheric pressure will be

• 700 m³

• 900 m³

• 1000 m³

• 500 m³

The Reynolds number of a flow is the ratio of

• gravity to viscous force

• gravity force to pressure force

• inertia force to viscous force

• viscous forces to pressure force

Rain drops are spherical in shape due to

• acceleration due to gravity

• downward motion

• surface tension

• capillary

Rain drops are spherical in shape, because of

• surface tension

• capillarity

• downward motion

• acceleration due to gravity

If a liquid is flowing through a horizontal tube, then $\mathrm{p} + \frac{1}{2}{\mathrm{\rho V}}^2$= constant. This shows that

• If p increases then V also increases

• p and V both are constant

• If p increases then V decreases

• If p decreases then V also decreases

Water wets the walls of its glass container due to the fact that

• cohesive force is greater than adhesive force

• cohesive force is equal to the adhesive force

• adhesive force is greater than the cohesive force

• cohesive and adhesive forces form action-reaction pair

189.

Surface tension of a detergent solution is 2.8 x 10^-2 Nm^-1. The work done in blowing a bubble of diameter 1 cm will be nearly

• 1.24 x 10^-4 J

• 1.76 × 10^-5 J

• 1.8 × 10^-3 J

• 2.4 x 10^-4 J

The surface tension and vapour pressure of water at 20°C is 7.28x10^-2 Nm^-1 and 2.33 x 10³ Pa respectively. The radius of the smallest spherical droplet which can form without evaporating is

• 6.25 x 10^-5 m

• 6.25 x 10^-3 m

• 7.45 x 10^-3 m

• 8.9 x 10^-4 m