$\sim (p \vee q) \vee (\sim p \wedge q)$ is logically equivalent to

Which of the following have $3C-2e^-$ bond?
$I.$ $Al_2Cl_6$
$II.$ $B_2H_6$
$III.$ $Fe_2Cl_6$
$IV.$ $Si_2H_6$

An inductance of $1 \ H$ is connected in series with an $AC$ source of $220 \ V$ and $50 \ Hz$. The inductive reactance (in ohm) is (in $pi$)

Which of the following substances would quickly absorb oxygen?

$A$ beaker contains $200\, g$ of water. The heat capacity of the beaker is equal to that of $20\, g$ of water. The initial temperature of water in the beaker is $20^\circ C$. If $440\, g$ of hot water at $92^\circ C$ is poured into it,the final temperature (neglecting radiation loss) will be nearest to $^\circ C$.

$A$ storehouse of collected plant specimens that are dried,pressed,and preserved on sheets is known as .........