Question

Assertion : $^{90}Sr$ from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.
Reason : The energetics $\beta$-particles emitted in the decay of $^{90}Sr$ damage the bone marrow.

• A. If both assertion arid reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false.

Answer 1

Answer: (A)

${ }_{38} Sr ^{90}$ decays to ${ }_{39} Y ^{90}$ when $\beta$-rays emission is occurred. Sr gets absorbed in bones along with calcium which causes impairment of the production of red blood cells
Now $ Sr ^{90} \stackrel{\beta}{\longrightarrow } Y^{90}$
Sr decay to Yitrium. $Sr ^{90}$ emits $\beta$-rays of very high energy. Bone marrow is damaged by these high energetic $\beta$-particles.