Question

1. Which of these two elements - A=2,8,1 and B = 2,8,8,1 is more electropositive? 2. Why does the size of the atoms progressively become smaller when we move from sodium (Na) to chlorine (Cl) in the third period of the period table ?

Answer 1

B is more electro positive
The size of atom gets smaller on going through period because effective nuclear charge per electron increases and the nucleus tend to pull the electrons towards the centre thus resulting in smaller size of atom.