For two radioactive nuclides X and Y, semi-log plots of their undecayed nuclei yield straight-line slopes −0.020h−1 and −0.050h−1 respectively. Which statement is correct?
a) X has a shorter half-life than Y
b) Both nuclides have identical half-lives
c) Y has a shorter half-life than X
d) The half-life cannot be compared without knowing their initial numbers of nuclei