MCQ
Beryllium’s fourth electron will have the four quantum numbers :
- A$n=1,l=0,m=0,s=+1/2$
- B$n=1,l=1,m=1,s=+1/2$
- ✓$n=2,l=0,m=0,s=-1/2$
- D$n=2,l=1,m=0,s=+1/2$
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Given :
Molar mass $N =14\,g\,mol ^{-1} ; O =16\,g\,mol ^{-1} ; C =12\,g\,mol ^{-1} ; H =1\,g\,mol ^{-1}$;

$\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\
{C{H_3}C{H_2} - O - C - C{H_2} - C - OH} \\
{||\,\,\,\,\,} \\
{O\,\,\,\,\,\,}
\end{array}$