MCQ
Which of the following is correct option?
- A$_{21}Sc = [Ar]\, 3d^1\, 4s^2$
- B$_{89}Ac = [Rn]\, 5f^0 \,6d^1 \,7s^2$
- C$_{29}Cu = [Ar] \,3d^{10} \,4s^1$
- ✓All are correct
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${C{H_3} - C{H_2} - CH = C{H_2} + HBr\,\to \,CH _{3}- CH _{2}- CH _{2}- C^{+}H _{2}+ Br ^{-}} _{"A"}$
${C{H_3} - C{H_2} - CH = C{H_2} + HBr\, \to \,CH _{3}- CH _{2}- C^{+}H - CH _{3}+ Br ^{-}}_{"B"}$
Reason : The concentration of salt content in the cells increases.


| Column $A$ | Column $B$ |
| $(i) \;\mathrm{Na}_{2} \mathrm{O}$ | $(a)$ Neutral |
| $(ii) \;\mathrm{Al}_{2} \mathrm{O}_{3}$ | $(b)$ Basic |
| $(iii)\;\mathrm{N}_{2} \mathrm{O}$ | $(c)$ Acidic |
| $(iv)\;\mathrm{Cl}_{2} \mathrm{O}_{7}$ | $(d)$ Amphoteric |
Which of the following options has all correct palrs