Fraunhofer lines are produced by the absorption of light in

The condition that $f(x)=a x^3+b x^2+c x+d$ has no extreme value,is

Which of the following does not contain $DNA$?

Which of the following compounds will be most easily attacked by an electrophile?

If $f(x) = \sqrt{ax} + \frac{a^2}{\sqrt{ax}}$,then $f^{\prime}(a)$ is equal to

$A$ body cools from $60\,^oC$ to $50\,^oC$ in $10\,minutes$. If the room temperature is $25\,^oC$ and assuming Newton's law of cooling to hold good,the temperature of the body at the end of the next $10\,minutes$ will be ......... $^oC$.