Question
Question: The order of decreasing ionisation enthalpy in alkali metals is....
The order of decreasing ionisation enthalpy in alkali metals is.
A
Na > Li > K > Rb
B
Rb < Na < K < Li
C
Li > Na > K > Rb
D
K < Li < Na < Rb
Answer
Li > Na > K > Rb
Explanation
Solution
: Ionisation enthalpy of alkali metals decreases down the group from Li to Cs. This is because of increases in size which outweighs the increasing nuclear charge, and the outermost electron is very well screened from the nuclear charge.