If $y=A \cos n x+B \sin n x$,then $y_2+n^2 y$ is equal to

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Linnaeus	$(i)$ First to discover viruses
$(B)$ Ivanowsky	$(ii)$ First to discover lichens
$(C)$ Iyengar	$(iii)$ Father of Indian Bryology
$(D)$ Tulasne	$(iv)$ Father of Taxonomy
$(E)$ Shiv Ram Kashyap	$(v)$ Father of modern Phycology in India

Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in $C_{2}H_{4}$ and $C_{2}H_{2}$ molecules.

Let $f: R-\{3\} \rightarrow R-\{1\}$ be defined by $f(x) = \frac{x-2}{x-3}$. Let $g: R \rightarrow R$ be given as $g(x) = 2x-3$. Then,the sum of all the values of $x$ for which $f^{-1}(x) + g^{-1}(x) = \frac{13}{2}$ is equal to

If the angle $2 \theta$ is acute,then the acute angle between the pair of straight lines $x^2(\cos \theta - \sin \theta) + 2xy \cos \theta + y^2(\cos \theta + \sin \theta) = 0$ is:

Which of the following statements is incorrect regarding $DDT$?