The electron in the hydrogen atom undergoes transition from higher orbitals to orbital of radius 211.6 pm. This transition is associated with :

50 mL of 0.2 M ammonia solution is treated with 25 mL of 0.2 M HCl. If pK_b of ammonia solution is 4.75, the pH of the mixture will be :

An ideal gas undergoes isothermal expansion at constant pressure. During the process :

If three positive numbers a, b and c are in A.P. such that abc = 8, then the minimum possible value of b is :