Which is an example of a highly unstable isotope that is often used in fission reactions?
a. c-12
b. c-14
c. u-235
d. u-238

C. U-235

Explanation:

A fission reaction is one in which an unstable radioisotope breaks down into smaller nuclei when bombarded with energetic particles.

The highly unstable isotope that is often used in fission reactions is U-235. When bombarded with neutrons that atom breaks down to form krypton and barium along with the release of a large amount of energy. The reaction is given as:

₉₂U²³⁵ +  ₀n¹  →   ₃₆Kr⁸⁹  +  ₅₆Ba¹⁴⁴  + 3₀n¹ + 210 Mev energy

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements