Question

What type of particle is emitted when U92238 decays to Th90234?

Answer 1

Answer: α particle

Explanation:-

A nuclear fission reaction is defined as the reaction in which a heavy nucleus splits into small nuclei along with release of energy.

The given reaction is

$^{238}_{92}\textrm{U}\rightarrow ^{234}_{90}\textrm {Th}+ ^{A}_{Z}\textrm{X}$

Now,  as the mass on both reactant and product side must be equal:

To calculate A:

Total mass on reactant side = total mass on product side

238 = 234 + A

A = 4

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

92 = 90 + Z

Z = 2

The particle with atomic number of 2 and mass number of 4 is $\alpha$ particle.  

$^{238}_{92}\textrm{U}\rightarrow ^{234}_{90}\textrm {Th}+ ^{4}_{2}{\alpha}$