Which one of the following pairs is incorrectly matched?

$A$ wire of length $l$ is bent into a circular coil of one turn of radius $R_1$. Another wire of the same material,same area of cross-section,and same length is bent into a circular coil of two turns of radius $R_2$. When the same current flows through the two coils,the ratio of magnetic induction at the centres of the two coils is

The work done in placing a charge of $8 \times 10^{-18} \ C$ on a capacitor of capacitance $100 \ \mu F$ is:

The orange coloured compound formed when $H_2O_2$ is added to $TiO_2$ solution acidified with conc $H_2SO_4$ is

$A$ particle of mass $M$ is moving in a horizontal circle of radius $R$ with uniform speed $v$. When it moves from one point to a diametrically opposite point,its

The alum used for purifying water is