Question

Which of the following order is wrong?

• A. $NH _{3}< PH _{3}< AsH _{3}-$ Acidic
• B. $Li < Be < B < C$ - First $IP$
• C. $Al _{2} O _{3}< MgO < Na _{2} O < K _{2} O -$ Basic
• D. $Li ^{+}< Na ^{+}< K ^{+}< Cs ^{+}-$ionic radius

Answer 1

Answer: (B)

$Li < Be < B < C$ - First $IP$

Answer 2

$Li \rightarrow 1 s ^{2} 2 s ^{1} ; Be \rightarrow 1 s ^{2} 2 s ^{2} ; B \rightarrow 1 s ^{2} 2 s ^{2} 2 p ^{1} ; C \rightarrow 1 s ^{2} 2 s ^{2} 2 p ^{2}$
$Li < B < Be < C$
$Be$ is having higher ionisation potential than $B$ as $Be$ is having fully filled $2 s -$ orbital due to which it gets extra stability.