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$n=2,l=1,m=0,s=+1/2$
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.


$C{O_{\left( g \right)}} + \frac{1}{2}{O_{2\left( g \right)}} \to C{O_{2\left( g \right)}}\,;\,\Delta H = - 300\,kJ$
${H_2}_{\left( g \right)} + \frac{1}{2}{O_2}_{\left( g \right)} \to {H_2}{O_{\left( g \right)}}\,;\,\Delta H = - 250\,kJ$
$C_{(s)} + O_{2(g)} \to CO_{2(g)} ; \Delta H = -x\, kJ$
The value of $x$ will be