Which of the following statements is incorrect for physical adsorption?

An infinitely long straight conductor is bent into the shape as shown below. It carries a current of $I$ ampere and the radius of the circular loop is $R$ metre. Then,the magnitude of magnetic induction at the centre of the circular loop is

$\sqrt{3} \operatorname{cosec} 20^{\circ} - \sec 20^{\circ}$ is equal to

Identify the product $(C)$ in the following series of reactions:
Cyclopentane $\xrightarrow{Br_2 (1 \ eq), h\nu} (A)$ $\xrightarrow{Alc. KOH} (B)$ $\xrightarrow{NBS} (C)$

Identify the incorrect statement among the following:

Identify phenacetin from the following.