The angular resolution of a $10\,cm$ diameter telescope at a wavelength of $5000\,\mathring{A}$ is of the order of:

Which of the following reacts with benzene in the presence of anhydrous aluminum chloride to form acetophenone?

The oxidation states of $S$ atoms in Caro's and Marshall's acids are

Laser beams are used to measure long distances because

$A$ bimetallic strip consists of metals $A$ and $B$. It is mounted rigidly at the base as shown. The metal $A$ has a higher coefficient of expansion than that of metal $B$. When the bimetallic strip is placed in a cold bath,it will:

Given below are $2$ statements:
Statement $I$: The number of species among $BF_4^-$, $SiF_4$, $XeF_4$ and $SF_4$, that have unequal $E-F$ bond lengths is $2$. Here, $E$ is the central atom.
Statement $II$: Among $O_2^-$, $O_2^{2-}$, $F_2$ and $O_2^+$, $O_2^-$ has the highest bond order.
In the light of the above statements, choose the correct answer from the options given below