$\alpha$-chlorosodium acetate on boiling with aqueous sodium nitrite gives

The bond angle $\mathrm{H}-\mathrm{O}-\mathrm{O}$ in $\mathrm{H}_2 \mathrm{O}_2$ in gaseous phase is

How many metameric ethers are represented by the molecular formula $\mathrm{C_4H_{10}O}$ ?

The activation energy of a reaction is zero. Its rate constant at 280 K is $1.6 \times 10^{-6} \mathrm{~s}^{-1}$, the rate constant at 300 K is