The compound prepared by a substitution reaction of benzene is

If the impurity in a metal has a greater affinity for oxygen and is more easily oxidised than the metal,then the purification of metal may be carried out by

Radioactive disintegration differs from a chemical change in being

To remove the second term of the equation $x^4-8x^3+x^2-x+3=0$,diminish the roots of the equation by

According to the law of equipartition of energy,the molar specific heat of a diatomic gas at constant volume,where the molecule has one additional vibrational mode,is:

$A$ narrow tube is bent in the form of a circle of radius $R,$ as shown in the figure. Two small holes $S$ and $D$ are made in the tube at positions right-angled to each other. $A$ source placed at $S$ generates a wave of intensity $I_0$ which is equally divided into two parts: one part travels along the longer path,while the other travels along the shorter path. Both the waves meet at the point $D$ where a detector is placed. The maximum value of $\lambda$ to produce a maxima at $D$ is given by