MCQ
Percentage of lead in lead pencil is:
- ✓$0$
- B$20$
- C$80$
- D$60$
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$\mathrm{H}_2, \mathrm{He}_2^{+}, \mathrm{O}_2^{+}, \mathrm{N}_2^{2-}, \mathrm{O}_2^{2-}, \mathrm{F}_2, \mathrm{Ne}_2^{+}, \mathrm{B}_2$