`._(92)^(238)Th` is a natural an `alpha`-emitter. After `alpha` emission, the residual `U_(X_(1))` in turns emits a `beta`-particles to produce nucleus `U_(X_(2))`. Find out the atomic number and mass number of `U_(X_(1))` and `U_(X_(2))`. Also if uranium belongs to IIIrd group to which group `U_(X_(1))` and `U_(X_(2))` belong.

Explanation

`._(92)^(238)U - ._(2)^(4)He to ._(90)^(234)U_(X_(1))`
`._(90)^(234)U_(X_(1)) - (._(-1)^(0)e) to ._(91)^(234)U_(X_(2))`
Both `U_(X_(1))` and `U_(X_(2))` will belong to IIIrd group because both lie in actinide series.