Question

Among the elements with atomic number 20 and 19 . Which has smaller radius? Write its oxides with molecular formula​

Answer 1

atomic number 20 is of Calcium(Ca)

atomic number 19 is of Potassium(K)

The atomic radius decreases along a period, so K comes before Ca in the 4th period, so:-

atomic radius of Calcium(Ca)<atomic radius of Potassium(K)

Oxide of calcium:-

$Ca^{+2}$+02-->Cao (valency of calcium as well as that of oxygen is 2)

Oxide of Potassium:-

$K^{+1}$+O2-->$K_{2}$O