Exhausted permutit does not contain ....... ion.

Hardening of oils is caused by

The nucleus of tritium contains

Hydrogen generally forms covalent compounds. Give reason.

Complete the following reactions:
$(i) \, H_{2(g)} + M_m O_{o(s)} \xrightarrow{\Delta }$
$(ii) \, CO_{(g)} + H_{2(g)} \xrightarrow[catalyst]{\Delta }$
$(iii) \, C_3 H_{8(g)} + 3 H_2 O_{(g)} \xrightarrow[catalyst]{\Delta }$
$(iv) \, Zn_{(s)} + NaOH_{(aq)} \xrightarrow{heat}$

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ Heavy water is used for the study of reaction mechanism.
Reason $(R):$ The rate of reaction for the cleavage of $O-H$ bond is slower than that of $O-D$ bond.
Choose the most appropriate answer from the options given below: