Which one of the following metals forms interstitial hydride easily?

Solution

Chemistry ma’am · 3 steps

Find each metal's group: groups 7, 8 and 9 sit in the hydride gap, and Cr in group 6 is just outside it.

1. Interstitial hydrides. Many d- and f-block metals take up hydrogen into the gaps of their crystal lattice. This gives non-stoichiometric (metallic) hydrides such as LaH_(2.87) and TiH_(1.5-1.8).
2. The hydride gap. The metals of groups 7, 8 and 9 do not form hydrides at all. In group 6, only chromium forms one, CrH. This gap in the periodic table is called the hydride gap.

   Metal	Group	Forms a hydride?
   Cr	6	Yes, CrH
   Mn	7	No, in the hydride gap
   Fe	8	No, in the hydride gap
   Co	9	No, in the hydride gap

3. So. Chromium is the only metal here that forms an interstitial hydride, so the answer is (a).

The idea to keep. Remember the hydride gap: groups 7, 8 and 9 form no hydrides, and in group 6 only chromium does (CrH). Find the group first and the answer follows.

Answer from the NTA final answer key. Solution by PrepWiser.