Which amino acid is encoded by only a single codon?

The first codon discovered by $Nirenberg$ and $Matthaei$ was:

The assumption that the genetic code is a triplet was suggested by:

Select the odd one out.

How many types of $tRNA$ are there?

For the genetic code,choose the correct option for the given statements. Where $T$ stands for True and $F$ stands for False.
$(1)$ Phenylalanine $(Phe)$ amino acid is coded by more than three codons.
$(2)$ The codon is read in $t-RNA$ in a contiguous fashion.
$(3)$ $UUC$ would code for phenylalanine.
$(4)$ $AUG$ codes for Methionine.