Restriction enzymes were discovered by

Consider the following statements. Which of the following statements are correct?
$(i)$ Froth floatation technique is used to concentrate sulphide ore.
$(ii)$ Froth floatation technique is based upon differential wettability of ore and impurity in water.
$(iii)$ Red Bauxite is concentrated by Bayer’s process.
$(iv)$ Carbon is used as reducing agent during extraction of zinc from zinc blende.

$A$ light beam is travelling from Region $I$ to Region $IV$ (refer figure). The refractive indices in Region $I, II, III$ and $IV$ are $n_0, \frac{n_0}{2}, \frac{n_0}{6}$ and $\frac{n_0}{8}$,respectively. The angle of incidence $\theta$ for which the beam just misses entering Region $IV$ is

The area (in sq units) bounded by the curves $y^2=4x$ and $x^2=4y$ is

Identify the major product formed when $2-$Methylhexan$-3-$ol is heated with concentrated sulphuric acid.

The surface of a metal is illuminated with light of wavelength $400 \, nm$. The kinetic energy of the ejected photoelectrons is found to be $1.68 \, eV$. The work function of the metal is .................. $eV$ $(hc = 1240 \, eV-nm)$.