How many nonsense codons are there?

The code of $mRNA$ and proteins are:

The diamond code proposal was made by:

There is only one possible sequence of amino acids when deduced from a given nucleotide sequence. However,multiple nucleotide sequences can be deduced from a single amino acid sequence. Explain this phenomenon.

Nirenberg synthesized an $m-RNA$ containing $34$ poly-adenine and found a $11$ poly-lysine polypeptide structure. This proves that the genetic code for lysine is ......

$A$ polypeptide is produced as dictated by $mRNA$. The number of bases on the $mRNA$ that code for the polypeptide portion containing the $N$-terminal amino acid and the next $13$ amino acids is: