In a completely opaque medium, if $50\%$ of the incident monochromatic radiation is absorbed, then which of the following statements are $CORRECT$

1. $50\%$ of the incident radiation is reflected
2. $25\%$ of the incident radiation is reflected
3. $25\%$ of the incident radiation is transmitted
4. No incident radiation is transmitted
1. $P$ and $S$ only
2. $Q$ and $R$ only
3. $P$ and $Q$ only
4. $R$ and $S$ only