Nucleoside analogs are the mutagenic chemicals that have a structure that is similar to the normal bases of the nucleotide and thus can be incorporated in the DNA during the process of replication, however as it has different base-pairing rules than the normal nucleotide base it can lead to mutations.
An example of a nucleoside analog is acyclovir which an analog of guanosine.
water can absorb a large amount of energy without a large rise in temperature. This is called heat capacity. As the sun shines on bodies of water, they absorbs great amount of its energy without a large fluctuation in temperature.