One mole of an ideal gas at 300 K in thermal contact with surroundings expands isothermally from 1.0 L to 2.0 L against a constant pressure of 3.0 atm. In this process, the change in entropy of surrounding ($$\Delta$$S_surr)in JK^–1 is (1L atm = 101.3 J)

The mole fraction of a solute in a solution is 0.1. At 298 K, molarity of this solution is the same as its molality. Density of this solution at 298 K is 2.0 g cm^–3 . The ratio of the molecular weights of the solute and solvent, $$\left( {{{M{W_{solute}}} \over {M{W_{solvent}}}}} \right)$$, is

According to the Arrhenius equation,

A plot of the number of neutrons (N) against the number of protons (P) of stable nuclei exhibits upward deviation from linearity for atomic number, Z > 20. For an unstable nucleus having N/P ratio less than 1, the possible mode(s) of decay is(are)