Multiple choice

Directions: Fill in the numbered blank (iii) with the best option from those given.

Directions: Fill in the numbered blank with the best option from those given.

Radium is a radioactive element. Let us see what “radioactive” _____ (i) ____. Radioactive elements do not change from year to year. But a few of the heaviest atoms break down and change into other kinds. This breakdown or ____ (ii) _____ is called “radio activity”. Each radioactive element _____ (iii) ____ by giving off rays at a certain rate. This rate cannot be _____ (iv) ____ or slowed down by any known method. Some changes occur rapidly, others slowly, but in all cases the action cannot be _____ (v) ______ by man.

  1. disintegrates

  2. divides

  3. multiplies

  4. freezes
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A Correct answer
Explanation

Each radioactive element disintegrates (breaks down) by giving off rays. "Disintegrates" precisely captures the atomic breakdown process in radioactive decay. "Divides" implies splitting into equal parts, "multiplies" means increasing in number, and "freezes" has no relevance to radioactive processes.

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