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If 50% of a radioactive substance dissociates in 15 min, then the time taken by substance to dissociate 99% will beA. 50 minB. 100 minC. 99 minD. 150 min |
Answer» Correct Answer - C Radioactive disintegration is a first order reaction, `k=(0.693)/(t_(1//2))=(0.693)/(15)" "(Given, t_(1//2)=15min)` =0.0462 Given, a=100, x=99 t=? `or" "0.0462=(2.303)/(t)"log"(100)/(100-99)` `=(2.303)/(t)" log "100` `or" "0.0462xxt =2.303xx2` `therefore" "t=(2.303xx2)/(0.0462)=99min` |
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