A water drop of radius 1 $$\mu$$m falls in a situation where the effect of buoyant force is negligible. Co-efficient of viscosity of air is 1.8 $$\times$$ 10^$$-$$5 Nsm^$$-$$2 and its density is negligible as compared to that of water 10⁶ gm^$$-$$3. Terminal velocity of the water drop is :

(Take acceleration due to gravity = 10 ms^$$-$$2)

A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat during BC and rejects 60 J of heat during CA. A work of 50 J is done on the gas during the part BC. The internal energy of the gas at A is 1560 J. The workdone by the gas during the part CA is :

What will be the effect on the root mean square velocity of oxygen molecules if the temperature is doubled and oxygen molecule dissociates into atomic oxygen?

Two point charges A and B of magnitude +8 $$\times$$ 10^$$-$$6 C and $$-$$8 $$\times$$ 10^$$-$$6 C respectively are placed at a distance d apart. The electric field at the middle point O between the charges is 6.4 $$\times$$ 10⁴ NC^$$-$$1. The distance 'd' between the point charges A and B is :