Identify the physical quantity that cannot be measured using spherometer :

Two bodies of mass $$4 \mathrm{~g}$$ and $$25 \mathrm{~g}$$ are moving with equal kinetic energies. The ratio of magnitude of their linear momentum is :

$$0.08 \mathrm{~kg}$$ air is heated at constant volume through $$5^{\circ} \mathrm{C}$$. The specific heat of air at constant volume is $$0.17 \mathrm{~kcal} / \mathrm{kg}^{\circ} \mathrm{C}$$ and $$\mathrm{J}=4.18$$ joule/$$\mathrm{~cal}$$. The change in its internal energy is approximately.

The radius of third stationary orbit of electron for Bohr's atom is R. The radius of fourth stationary orbit will be: