Q42. For a reaction $\mathrm { A } \xrightarrow { \mathrm { K } _ { 1 } } \mathrm {~B} \xrightarrow { \mathrm {~K} _ { 2 } } \mathrm { C }$ If the rate of formation of $B$ is set to be zero then the concentration of $B$ is given by :\\
(1) $\left( \mathrm { K } _ { 1 } + \mathrm { K } _ { 2 } \right) [ \mathrm { A } ]$\\
(2) $\left( \mathrm { K } _ { 1 } / \mathrm { K } _ { 2 } \right) [ \mathrm { A } ]$\\
(3) $\left( \mathrm { K } _ { 1 } - \mathrm { K } _ { 2 } \right) [ \mathrm { A } ]$\\
(4) $\mathrm { K } _ { 1 } \mathrm {~K} _ { 2 } [ \mathrm {~A} ]$