Given below are two reactions, involved in the commercial production of dihydrogen (H$$_2$$). The two reactions are carried out at temperature "T$$_1$$" and "T$$_2$$", respectively

$$C(s) + {H_2}O(g)\buildrel {{T_1}} \over \longrightarrow CO(g) + {H_2}(g)$$

$$CO(g) + {H_2}O(g)\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Catalyst}^{{T_2}}} C{O_2}(g) + {H_2}(g)$$

The temperatures T$$_1$$ and T$$_2$$ are correctly related as :

Which of the following can reduce decomposition of $$\mathrm{H}_{2} \mathrm{O}_{2}$$ on exposure to light :

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : Loss of electron from hydrogen atom results in nucleus of $$\sim 1.5 \times 10^{-3} \mathrm{pm}$$ size.

Reason R : Proton $$\left(\mathrm{H}^{+}\right)$$ always exists in combined form.

In the light of the above statements, choose the most appropriate answer from the options given below:

The starting material for convenient preparation of deuterated hydrogen peroxide ($$\mathrm{D_{2}O_{2}}$$) in :