The graph shows the variation of activity with time for a sample of a nuclide X.
What was the initial number of nuclei of X in the sample?
3.5×1053.5 \times 10^53.5×105
2.4×1082.4 \times 10^82.4×108
3.5×1083.5 \times 10^83.5×108
4.9×1084.9 \times 10^84.9×108
