- A$Be < B < C < N < O$
- ✓$B < Be < C < O < N$
- C$Be > B > C > N > O$
- D$B < Be < N < C < O$
On moving from left to right in a period, with increase in the atomic number, the ionisation enthalpy increases.
However there are few exceptions
$(1)$ Ionization energy of $B\,<\,$ ionization energy of $B e$. This is because less amount of energy is required to remove a p electron than s electron from the same principal quantum shell.
$(2)$ Ionization energy of $O\, <\,$ ionization energy of $N$.
Nitrogen has half filled $2 p$ subshell which is very stable. More energy is required for removal of electron from half filled, stable subshell.
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Upon treatment with dilute alkaline $KMnO _4, P$ as well as $Q$ could produce one or more than one from $S , T$ and $U$.$Image$
$1.$ Compounds formed form $P$ and $Q$ are, respectively
$(A)$ Optically active $S$ and optically active pair $(T, U)$
$(B)$ Optically inactive $S$ and optically inactive pair $(T, U)$
$(C)$ Optically active pair $(T, U)$ and optically active $S$
$(D)$ Optically inactive pair $(T, U)$ and optically inactive $S$
$2.$ In the following reaction sequences $V$ and $W$ are respectively :$Image$
mcq $Image$
Give the answer question $1$ and $2.$
$(i)\, H_3PO_4+H_2O \rightarrow H_3O^+ + H_2PO_4^-$
$(ii)\, H_2PO 4^- + H_2O \rightarrow HPO_4^{2-} + H_3O^+$
$(iii)\, H_2PO_4^-+ OH^- \rightarrow H_3PO_4 + O^{2-}$
In which of the above does $H_2PO_4^-$ act as an acid ?