3. Classification of elements and periodicity in properties — Chemistry STD 11 Science — Question

$\mathrm{C}\mathrm{H}_{3} -\mathrm{C} \equiv \mathrm{CH} \xrightarrow[873\;K]{\text { red hot iron tube}} \mathrm{A}$

the number of sigma$(\sigma)$ bonds present in the product $A$ is

$N _{2} O _{4}( g ) \rightleftharpoons 2 NO _{2}( g ) ; \Delta H ^{0}=+58 kJ$

For each of the following cases $(a, b),$ the direction in which the equilibrium shifts is:

$(a)$ Temperature is decreased

$(b)$ Pressure is increased by adding $N _{2}$ at constant $T$