81.
When metal $$'M'$$ is treated with $$NaOH$$ , a white gelatinous precipitate $$'X'$$ is obtained, which is soluble in excess of $$NaOH$$. Compound $$'X'$$ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal $$'M'$$ is:
No explanation is given for this question. Let's discuss the answer together.
85.
Consider the following sequence of reaction.
\[Na+N{{H}_{3}}\left( g \right)\to \left[ X \right]\xrightarrow{{{N}_{2}}O}\left[ Y \right]\xrightarrow{\text{Heat}}\underset{\text{Gas Pure}}{\mathop{\left[ Z \right]}}\,\]
Identify $$(Z)$$ gas :
\[Na+N{{H}_{3}}\left( g \right)\xrightarrow{\Delta }\underset{\left[ X \right]}{\mathop{NaN{{H}_{2}}}}\,\] \[\xrightarrow{{{N}_{2}}O}\underset{\left[ Y \right]}{\mathop{Na{{N}_{3}}}}\,\xrightarrow{\Delta }\underset{\left[ Z \right]}{\mathop{{{N}_{2}}\uparrow }}\,\]
86.
The reaction of zine with dilute and concentrated nitric acid, respectively, produces:
The electron affinity decreases from $$Cl \to Br \to I,$$ i.e. on moving down the group.
However, electron affinity of fluorine is unexpected low. It cannot be explained by any simple mechanism. It is probably due to small size of the atom. The addition of an extra electron produces high electron charge density in a relatively compact $$2p$$ subshell resulting in strong electron-electron repulsion. The repulsive forces between electrons imply low electron affinity. So, the correct order of electron affinity for halogens is $$I < Br < F < Cl$$
89.
The oxidation state of sulphur in the anions $$SO_3^{2 - },{S_2}O_4^{2 - }$$ and $${S_2}O_6^{2 - }$$ follows the order