S Block Elements Question 108
Question: The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrides decreases in which of the following orders-
Options:
A) $ CsH>RbH>KH>NaH>LiH $
B) $ KH>NaH>LiH>CsH>RbH $
C) $ NaH>LiH>KH>RbH>CsH $
D) $ LiH>NaH>KH>RbH>CsH $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] The stability of alkali metal hydrides decreases from $ Li $ to $ Cs $ .
It is due to the fact that $ M-H $ bonds become weaker with increase in size of alkali metals as we move down the group from $ Li $ to $ Cs $ .
Thus the order of stability of hydrides is $ LiH>NaH>KH>RbH>CsH $
BETA
