NEET Physics Nuclei Questions Solved


A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is

(a) 120 min                   (b) 80 min
(c) 30 min                     (d) 20 min

(d) A=A012n30=24012n123=12nn=3

tT1/2=3T1/2=t3=13hr=20 min

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