Additin of sodium hydroxide solution to a weak acid (HA)results in a buffer of pH 6. If ionition constant of HA is 10^$$-$$5, the ratio of salt to acid concentration in the buffer solution will be :

The rate of a reaction A doubles on increasing the temperature from 300 to 310 K. By how much, the temperature of reaction B should be Increased from 300 K so that rate doubles if activation energy of the reaction B is twice to that of reaction A.

The pair of compounds having metals in their highest oxidation state is :

The enthalpy change on freezing of 1 mol of water at 5^oC to ice at −5^oC is :

(Given $$\Delta $$_fusH = 6 kJ mol^$$-$$1 at 0^oC,
C_p(H₂O, $$\ell $$ = 75.3J mol^$$-$$1 K^$$-$$1)
C_p(H₂O s) =36.8 J mol^$$-$$1 K^$$-$$1)