An element group-III with atomic number 92 and mass number 238 undergoes decay of one `alpha` particle. The newely formed element belongs to

The emission of penetraing alpha , beta particle (""_(2) ^(4) He and ""_(-1)^(0)e respectively ) along with gamma - radiation (hv) was noticed from unstable nuclei . All elements having Z gt 82 show this phenomenon . The emission was explained in terms of low binding energy (giving alpha - decay) high n/p ratio (neutron decay) , gamma from a radioactive nuclide is secondary emission. An element of group III with At. no. 90 and mass number of 238 undergoes decay of one alpha - particle . The newly formed element belongs to :

A radioactiv element has atomic number A and mass number M. It emits one alpha - particle .The atomic number and mass number of new element will be

._(90)Th a member of III group on losing alpha- particles forms a new element belonging to:

""_(90)Th , a member of III group on losing alpha -particle forms a new element belonging to

The element with atomic number 12 belongs to ….. group and…... period.

The element with atomic number 12 belongs to ……… group and …. Period