Which of the following is an opiate narcotic?

If $m \begin{bmatrix} -3 & 4 \end{bmatrix} + n \begin{bmatrix} 4 & -3 \end{bmatrix} = \begin{bmatrix} 10 & -11 \end{bmatrix}$,then $3m + 7n$ is equal to

$(\sqrt{3}+i)^7+(\sqrt{3}-i)^7$ is equal to (in $\sqrt{3}$)

The number of normals drawn to the parabola $y^2 = 4x$ from the point $(1, 0)$ is

Which one of the following pairs of gases are the major cause of 'Greenhouse effect'?

In a $U$-tube experiment,a column $AB$ of water is balanced by a column $CD$ of oil,as shown in the figure. Then the relative density of oil is