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NEET-XII-Physics

exam-2 year:2016

with Solutions - page 2
Qstn# 109 Prvs-QstnNext-Qstn
  • #109
    The half-life of a radioactive substance is 30 minutes.
    The time (in minutes) taken between 40% decay and
    85% decay of the same radioactive substance is :-
    (1) 45
    (2) 60
    (3) 15
    (4) 30
    digAnsr:   2
    Ans : (2)
    Sol. decay 40% 85%
    Remaining 60% 15%
    60%
    1
    2
    t
     30%
    1
    2
    t
     15%
    ∴t = 2t1/2 = 60 min.