The enthalpies of all elements in their standard states are:

(i) unity

(ii) zero

(iii) < 0

(iv) different for each element

Choose the correct answer. A thermodynamic state function is a quantity

(i) used to determine heat changes

(ii) whose value is independent of the path

(iii) used to determine pressure volume work

(iv) whose value depends on temperature only.

For the process to occur under adiabatic conditions, the correct condition is:

(i)

(ii)

(iii) q = 0

(iv) w = 0

of combustion of methane is – X kJ mol^–1. The value of DH0 is

(i) =

(ii) >

(iii) <

(iv) = 0

The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are, –890.3 kJ mol^–1 –393.5 kJ mol^–1, and –285.8 kJ mol^–1 respectively. Enthalpy of formation of CH₄(g) will be

(i) –74.8 kJ mol^–1 (ii) –52.27 kJ mol^–1

(iii) +74.8 kJ mol^–1 (iv) +52.26 kJ mol^–1