One gram of a radioactive sample of half-life 10min is sealed in a capsule at time t=0 .Amount of sample decayed up to 5 min is

Use the relation N=N0e−λt where the decay constant λ=(0.693/Thalf). The half life period Thalf is given to be 10 min, The amount N of radioactive out to be about 0.707g, so that the amount of sample decayed is (1−0.707)=0.293g.