When a plane mirror is rotated through an angle $\theta$,the reflected ray turns through an angle $2\theta$. What happens to the size of the image?

The value of $m$,such that the line $\frac{x-4}{1}=\frac{y-2}{1}=\frac{z-m}{2}$ lies in the plane $2x-4y+z=7$,is

Among the electrolytes $Na_2SO_4$,$CaCl_2$,$Al_2(SO_4)_3$ and $NH_4Cl$,the most effective coagulating agent for $Sb_2S_3$ sol is

The major product of the following reaction is

$A$ vessel contains $1$ mole of $O_2$ gas (molar mass $32$) at a temperature $T$. The pressure of the gas is $P$. An identical vessel containing $1$ mole of $He$ gas (molar mass $4$) at a temperature $2T$ has a pressure of:

Which of the following statements is correct regarding the ease of dehydration of alcohols?