Question

Which one of the following metals forms interstitial hydride easily ?

JEE MAINS 2021

• A. $Cr$
• B. $Mn$
• C. $Co$
• D. $Fe$

Answer 1

The correct option is A $Cr$

$Cr$ has tendency to form hydride easily

Elements of group $7,8,9$ do not form hydrides thus $Cr$ will only form hydride among the given elements $(Fe,Mn,CO)$

The low affinity of the elements of the group $6,7.8\text{and}9$ towards hydrogen when in their normal oxidation states prevent the formation of their metal hydrides. This is known as hydride gap. The region of the periodic table from group $7to9$ is referred to as the hydride gap as they do not form hydrides. Examples of such elements are as follows: $Mo,WandMn,Fe,Co,Ruetc.$

In the group $6$, chromium $\left(Cr\right)$ is an exception as it is the only group $6$ element to form a metal hydride. The metals like chromium absorb hydrogen in almost $1:1$ stoichiometric quantity.

During the formation of these type compounds hydrogen atoms occupy the interstitial sites present in the crystals of metals which are not available in case of other elements of the group.

Hence, option (b) is correct.