The acid used for making permanent markings on the glass surface is:

$A$ mixture of concentrated $HCl$ and concentrated $HNO_3$ in a $3:1$ ratio contains which of the following?

The bleaching action of bleaching powder is due to the formation of

$K_2Cr_2O_7 +$ conc. $H_2SO_4 + NaCl \rightarrow$ red orange vapours. Here red orange vapours are of :

Which of the following statements is correct regarding halogens?

Which of the following properties of halogens increase with increasing atomic number?
$(I)$ Ionization energy $(II)$ Ionic radius
$(III)$ Bond energy of the $X_2$ molecule $(IV)$ Enthalpy of vaporisation