Explain why $DNA$ is more stable than $RNA$ as a genetic material.

(A) $DNA$ is the predominant genetic material,as established by the Hershey-Chase experiments.
For a molecule to act as a genetic material,it must fulfill the following criteria:
$(i)$ It should be able to generate its replica (replication).
$(ii)$ It should be chemically and structurally stable.
$(iii)$ It should provide the scope for slow changes (mutation) that are required for evolution.
$(iv)$ It should be able to express itself in the form of 'Mendelian characters'.
If we consider the principle of base pairing and complementarity,both $DNA$ and $RNA$ can replicate. Proteins fail to fulfill this criterion.
The stability of genetic material is essential,as it should not change with different stages of the life cycle,age,or changes in the physiology of the organism.
This stability is evident from Griffith's 'Transforming Principle',where heating the bacteria did not destroy the properties of the genetic material.
Even if the two strands of $DNA$ are separated by heating,they can come together under appropriate conditions.
In $RNA$,every nucleotide has a $2'-OH$ group present as a reactive group,which makes $RNA$ unstable and easily degradable.
Compared to $RNA$,$DNA$ is chemically less reactive and structurally more stable. Thus,$DNA$ is a better genetic material.
$DNA$ also gains additional stability due to the presence of thymine instead of uracil.
Both $DNA$ and $RNA$ can mutate,but $RNA$ is unstable and mutates at a faster rate. Consequently,viruses with $RNA$ genomes,having shorter life spans,mutate and evolve faster.
$RNA$ can directly code for protein synthesis and can easily express characters,whereas $DNA$ is dependent on $RNA$ for protein synthesis.
Thus,while both $RNA$ and $DNA$ can function as genetic material,$DNA$ is more stable and preferred for the storage of genetic information,while $RNA$ is better suited for the transmission of genetic information.