Question

Which of the following is ${e^ - }$ rich hydride:-
1. $N{H_3}$
2. $CH4$
3. $B{H_3}$
4. $Ca{H_2}$

Answer 1

Hint : Electron rich hydrides are hydrogen compounds that react with other elements that have extra electrons in their lone pairs or atoms. The hydrides that have a proclivity for accepting electrons in order to form an octet.
Electron-rich hydrides are formed when elements in groups 15-17 combine to create compounds ( $N{H_3}$ has one lone pair, water has two and $HF$ has three lone pairs).

Complete Step By Step Answer:
Dihydrogen reacts with practically all elements except noble gases to generate hydrides under specified reaction conditions. Electron-rich hydrides are compounds of hydrogen with other elements that have excess electrons present as lone-pairs, as the name implies. Ammonia $-N{H_3}$ is a nitrogen hydride with one lone pair, water $\left( {{H_2}O} \right)$ is an oxygen hydride with two lone pairs, and so on. Because these species have a lot of electrons, they can transfer electrons, making them Lewis bases.
From the above gathered information we can conclude that $N{H_3}$ is ${e^ - }$ rich hydride.
So, the correct option is: (1) $N{H_3}$ .

Additional Information:
Ammonia is an amidase inhibitor and neurotoxic that is made up of a single nitrogen atom covalently linked to three hydrogen atoms. Bacterial activities and the decomposition of organic matter produce it both artificially and naturally. Ammonia is a chemical that is utilised in a variety of industrial processes, as well as as a fertiliser and a refrigerant. It is a colourless gas or compressed liquid with a pungent odour that can be inhaled, ingested, or come into touch with.

Note :
When forming a dative or coordinate connection, an electron-rich molecule is referred to as a Lewis base (in other words relatively weak so that it repeatedly forms and dissociates at or near room temperature).