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One mole of a present in a closed vessel undergoes decay as `""_(z)""^(m)Ato""_(Z-4)""^(m-8)B+2""_(2)""^(4)He`. The volume of He collected at NTP a fter 20 days is (`t""_(1//2)=10`days)A. 11.2 litreB. 22.4 litreC. 33.6 litreD. 67.2 litre |
Answer» Correct Answer - c Amount of (A)left=`N""_(0)/2""^(2)(t""_(1//2)xxn=T)` Amount of (A) decayed=`N""_(0)-N""_(0)/2=(3N(0))/4` `therefore` Mole of He formed=`2xx3/4N""_(0)` `=3/2N""_(0)=3/2`mole(`because` 1 mole of (A) is taken) `therefore` volume of He =`3/2xx22.40=33.6` litre |
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