Answers:
thorium-234
Explaination:
Isotopes are defined as the variants of a particular chemical element obtained by radioactive decay which makes it differ in neutron number and nucleon number but have the same number of protons in each atom.
Uranium-238 produces thorium-234 by alpha decay. alpha particle is a helium nucleus which carry 2 neutrons andn 2 protons with the mass number 4. In alpha decay, nucleus emits alpha particles which tranforms or decay into an atom with a mass number 4 less and an atomic number 2 less.
The equation for alpga decay is attached below:
Hence, the isotope is thorium-234 .