If the values of $\Lambda_{\infty}$ of $NH_4Cl, NaOH$ and $NaCl$ are $130, 217$ and $109 \ \Omega^{-1} \ cm^2 \ equiv^{-1}$ respectively,the $\Lambda_{\infty}$ of $NH_4OH$ in $\Omega^{-1} \ cm^2 \ equiv^{-1}$ is

The formula of ferrocene is

$A$ plot of the kinetic energy $\left(\frac{1}{2} m v^2\right)$ of ejected electrons as a function of the frequency $(\nu)$ of incident radiation for four alkali metals $(M_1, M_2, M_3, M_4)$ is shown below.
The alkali metals $M_1, M_2, M_3$ and $M_4$ are,respectively:

$A$ micelle formed during the cleansing action by soap is

On the basis of the following $E^o$ values,the strongest oxidizing agent is:
$[Fe(CN)_6]^{4-} \rightarrow [Fe(CN)_6]^{3-} + e^-$; $E^o = -0.35 \ V$
$Fe^{2+} \rightarrow Fe^{3+} + e^-$; $E^o = -0.77 \ V$

The half-life of a radioactive substance is $20 \text{ minutes}$. The approximate time interval $(t_2 - t_1)$ between the time $t_2$ when $3/4$ of it has decayed and time $t_1$ when $1/4$ of it has decayed is: