If $^nP_4 = 30 \times ^nC_5$,then $n = \dots$

Oxidation states of $P$ in $H_4P_2O_5, H_4P_2O_6, H_4P_2O_7$ are respectively:

$A$ monoatomic ideal gas,initially at temperature $T_1$,is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature $T_2$ by releasing the piston suddenly. If $L_1$ and $L_2$ are the lengths of the gas columns before and after the expansion respectively,then the ratio $\frac{T_2}{T_1}$ is:

The experimentally determined molar mass of a non-volatile solute,$BaCl_2$,in water by Cottrell's method,is

Which polymer is used as a lubricant and an electrical insulator?

If the variable line $y = kx + 2h$ is tangent to an ellipse $2x^2 + 3y^2 = 6$,then the locus of $P(h, k)$ is a conic $C$ whose eccentricity equals