c
\(1 \,curie = 3.71 \times 10^{10} \, disintegration/sec\)

\(6.02 \times 10^{23} \,atoms \,of \,{U^{234}} = 234\,gm\)

\(\therefore Mass \,of \,3.7  \times \,10^{10} \,atoms \,= \frac{{234 \times 3.71 \times {{10}^{10}}}}{{6.02 \times {{10}^{23}}}} = 1.48 \times {10^{ - 11}}\,gm\)