Genes of interest can be selected from a genomic library by using

Which of the following is not a Lewis acid?

If the direction cosines of two lines are given by $l+m+n=0$ and $l^2-5m^2+n^2=0$,then the angle between them is

Let $k$ be a non-zero real number. If $f(x) = \begin{cases} \frac{(e^x - 1)^2}{\sin(\frac{x}{k}) \log(1 + \frac{x}{4})} & x \neq 0 \\ 12 & x = 0 \end{cases}$ is a continuous function,then the value of $k$ is:

In mammals,histamine is secreted by .........

The area (in square units) of the region bounded by $x^2=8y$,$x=4$ and the $X$-axis is: