The molarity of pure water is

In a quadrilateral $ABCD$,the point $P$ divides $DC$ in the ratio $1:2$ and $Q$ is the midpoint of $AC$. If $\overrightarrow{AB}+2\overrightarrow{AD}+\overrightarrow{BC}-2\overrightarrow{DC}=k\overrightarrow{PQ}$,then $k$ is equal to

If $\frac{^{n+2}C_6}{^{n-2}C_2} = 11$,then $n$ satisfies the equation

The total number of valence electrons in $4.2 \, g$ of $N_3^-$ ion is ......... $N_A$. ($N_A$ = Avogadro number)

We have two spheres,one of which is hollow and the other solid. They have identical masses and moments of inertia about their respective diameters. The ratio of their radii is given by

What do pesticides include?