A metamer is an isomer having the same molecular formula, the same functional group, but different alkyl/aryl groups on either side of the functional group.
Hence, option (4) is the correct metamer.
For the thermal decomposition of \( N_2O_5(g) \) at constant volume, the following table can be formed, for the reaction mentioned below: \[ 2 N_2O_5(g) \rightarrow 2 N_2O_4(g) + O_2(g) \] Given: Rate constant for the reaction is \( 4.606 \times 10^{-2} \text{ s}^{-1} \).