$1$. Radioactive pollution is very dangerous since it can cause abnormal growth.
$2$. The Chernobyl nuclear accident happened made the area uninhabitable.
$3$. Fossil fuels such as coal or oil are burned, so acid gases are produced.
$4$ .Because of the dangerous acid rain, tree's leaves are damaged.
$5$.Because leaves are damaged, the tree cannot get enough food energy to stay healthy.