Which of the following is not an ore of magnesium?

An aqueous solution of $6.3 \ g$ of oxalic acid dihydrate is made up to $250 \ mL$. The volume of $0.1 \ N \ NaOH$ required to completely neutralize $10 \ mL$ of this solution is ............. $mL$.

The oxidation state and covalency of $Al$ in $[AlCl(H_2O)_5]^{2+}$ are respectively

An enzyme that can stimulate germination of barley seeds is

Which one of the following exhibits enantiomerism?

$A$ tank with vertical walls is mounted so that its base is at a height $H$ above the horizontal ground. The tank is filled with water to a depth $h$. $A$ hole is punched in the side wall of the tank at a depth $x$ below the water surface. To have maximum range of the emerging stream, the value of $x$ is