Thorn is a modified branch because:

$\tanh ^{-1}\left(\frac{1}{2}\right)+\operatorname{coth}^{-1}(2)$ is equal to

The oxidation number of $Pt$ in $[Pt(C_2H_4)Cl_3]^-$ is

$\lim _{x \rightarrow 8} \frac{\sqrt{1+\sqrt{1+x}}-2}{x-8}$ is equal to

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

Two blocks of masses $1 \ kg$ and $2 \ kg$ are connected by a metal wire going over a smooth pulley. The breaking stress of the metal is $\frac{40}{3 \pi} \times 10^6 \ N m^{-2}$. What should be the minimum radius of the wire used if it should not break (in $mm$)? $\left(g = 10 \ m s^{-2}\right)$