In gel electrophoresis,the separated bands of $DNA$ are cut out and extracted from the gel piece. This step is called

In the $Al_{2}Cl_{6}$ dimer,which of the following statements is true regarding the $Al-Cl$ bonds?

When alcohol vapor is passed over heated reduced copper $(Cu)$,the alcohol is converted into an alkene. Which type of alcohol is this?

Two oxides of nitrogen,$NO$ and $NO_2$,react together at $253 \ K$ to form a compound of nitrogen $X$. $X$ reacts with water to yield another compound of nitrogen $Y$. The shape of the anion of $Y$ molecule is:

$A$ magnetic needle lying parallel to a magnetic field is turned through $60^{\circ}$. The work done on it is $W$. The torque required to maintain the magnetic needle in the position mentioned above is

Identify $A$ and $B$ in the following reaction:
$C_2H_5Cl \xrightarrow{A} C_2H_5OH \xleftarrow{B} C_2H_5Cl$