Which metals are used in a gene gun for the insertion of alien $DNA$ into a competent host?

Genes of interest can be selected from a genomic library by using

Identify the palindromic sequence in the following:

Statement-$I$: Thermostable $\text{DNA}$ polymerase is isolated from $\text{Thermus aquaticus}$.
Statement-$II$: $\text{Taq}$ $\text{DNA}$ polymerase is inactive at high temperature $(72^{\circ}\text{C})$.

Which vector can clone small pieces of $DNA$?

Which of the following is not a palindromic $DNA$ sequence?