A radioactive nuclide has a half-life of $2.0$ hours. The decay rate for a sample of this nuclide is recorded at intervals of $1.0$ hour. The table lists the readings, with one entry replaced by $X$. Time / hours vs decay rate / $\text{decays s}^{-1}$: $0 \rightarrow 240$ $1.0 \rightarrow 170$ $2.0 \rightarrow 120$ $3.0 \rightarrow 85$ $4.0 \rightarrow X$ What is the most likely value of $X$?
- A15
- B42
- C50
- D60