Question

2016
Q.9 An atom of element Z has 39 neutrons and 18 protons in its nucleus. What are the (i) Mass
number (ii) Valence electron and (iii) Group number of Z? 3
2017
der of their increasing metallic character
NR.
lands​

Answer 1

Answer:

Mass number=18+39=57

Valence electron=8

Group number =8