Question

${}_{90}Th$ a member of III group on losing $\alpha$-particles forms a new element belonging to :

• A. I group
• B. III group
• C. II group
• D. IV group

Answer 1

The correct option is C II group

${}_{90}^{232}Th$ forms ${}_{88}^{228}Ra$ belonging to group II.
${}_{90}^{232}Th{\to }_{88}^{228}Ra{+}_2^{4}He$