Four elements A, B, C and D along with their electronic configuration are given below :

Elements A B C D
Electronic configuration 2,1 2,8 2,8,1 2,8,8

Now answer the following questions :

(i) which two elements belong to the same period ?

(ii) Which two elements belong to the same group ?

(iii) Which element out of A and C is more reactive and why?

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1 Answers

(i) A and B, C and D have the same period.

(ii) A and C have one valence electron, so the same group.

(iii) C is more reactive because C is placed below A in the periodic table and reactivity increases down the group.

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