Three parts of $conc. HCl$ and one part of $conc. HNO_3$ are mixed to form aqua regia. It is used to dissolve:

$HBr$ and $HI$ can reduce $H_2SO_4$,$HCl$ can reduce $KMnO_4$,and $HF$ can reduce:

Fluorine is a stronger oxidising agent than chlorine because :
$(a)$ $F-F$ bond has a low enthalpy of dissociation.
$(b)$ Fluoride ion $(F^{-})$ has high hydration enthalpy.
$(c)$ Electron gain enthalpy of fluorine is less negative than chlorine.
$(d)$ Fluorine has a very small size.
Choose the most appropriate answer from the options given :

When cold $NaOH$ reacts with $Cl_2$,which of the following is formed?

What are the products formed when fluorine reacts with dilute $NaOH$ and concentrated $NaOH$,respectively?

Marine plants are an important source of ........ .