Which of the following group of codons is called stop codons?

The degenerate nature of the genetic code is primarily associated with which position of the codon?

Statement $P$: An $m-RNA$ consists of $75$ nucleotides.
Statement $Q$: There are $61$ types of codons in the cytoplasm.

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.

Which of the following statements regarding the genetic code is incorrect?
$i.$ The codon is a triplet.
$ii.$ $64$ codons code for amino acids.
$iii.$ The genetic code is unambiguous.
$iv.$ The genetic code is universal.
$v.$ $AUG$ has dual functions.

$A$ mature $mRNA$ consists of $900$ bases without any stop codon in between. Calculate the number of amino acids coded by this $mRNA$ during translation.