Physics 2010 JAMB Past Questions - Question 46: The radioisotope ²³â�µâ‚‰â‚‚ U decays by emitting two alpha particles ,three beta particles and gamma ray.What is the mass an atomic numbers of the resulting daughter element ?

Correct Answer

A

Explanation

Uranium-235 (235U) decays into a daughter element through a series of nuclear reactions, which can be described as follows:

1. Uranium-235 (235U) undergoes alpha decay, emitting an alpha particle (α), which is a helium-4 nucleus (4He):

  235U -> 231Th + 4He

2. Thorium-231 (231Th) is now the daughter nucleus. It undergoes beta decay, emitting a beta particle (β-), which is an electron (e-):

  231Th -> 231Pa + e-

3. Protactinium-231 (231Pa) also undergoes beta decay:

  231Pa -> 231U + e-

4. Uranium-231 (231U) further decays by emitting an alpha particle:

  231U -> 227Th + 4He

5. Thorium-227 (227Th) undergoes a series of alpha and beta decays until it eventually stabilizes as a stable daughter element, in this case, it decays to Actinium-227 (227Ac).

At this point, the daughter element is Actinium-227 (227Ac).

The atomic number of an element is determined by the number of protons in its nucleus. In this case, the atomic number of the daughter element (227Ac) is 89 because it has 89 protons in its nucleus.

The mass number of an element is the sum of the protons and neutrons in its nucleus. The mass number of 227Ac is determined by adding the number of protons (atomic number) to the number of neutrons. You would need to consult a periodic table or a nuclear data source to find the exact mass number of 227Ac.