Thorium Th produces a daughter nucleus that is radioactive. The daughter, in tur

Question

Thorium

Th

produces a daughter nucleus that is radioactive. The daughter, in turn, produces its own radioactive daughter, and so on. This process continues until lead

Pb

is reached.

Concepts:
(i) How many of the 90 protons in the thorium nucleus are carried off by the ? particles? (Give your answer in terms of the number of ? particles N?.)

N?2N?    3N?4N?

(ii) How many protons are left behind when the ?? particles are emitted? (Choose the number of protons added to the nucleus due to the emission of ??particles. Give your answer in terms of the number of ?? particles N?.)

0N?    2N?3N?

(iii) How many of the 228 nucleons in the thorium nucleus are carried off by the ? particles? (Give your answer in terms of the number of ? particles N?.)

N?2N?    3N?4N?

(iv) Does the departure of a ?? particle alter the number of nucleons?

YesNo   

Explanation / Answer

i)

In ? particle decay 2 protons are carried of from a nucleus.

22490Th à 22088Th + 21284Pb +      3 42?

No protons carried of = 3N?

ii)

When –? particle is emitted 1 proton is added to the nucleus.

No protons added = 1N?

iii)

In ? particle decay 2 protons & 2 neutrons are carried of from a nucleus. Thus total 4 nucleons are carried off.

22490Th à 22088Th + 21284Pb +      3 42?

Since there is 3 times alpha decay , no of nucleons = 3*4 = 12

iv) Yes

When –? particle is emitted 1 proton is added to the nucleus. Thus 1 nucleon is added in the nucleus.

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