An inflated balloon shrinks when placed in a freezer because the 

The compound in which the oxidation state of nitrogen is + 3 is

Na\(_2\)X ⇌  2Na\(^+\)  +  X\(^{2-}\)

The bond between Na and X is likely to be

The compound responsible for the pleasant scent of fruits and perfumes belongs to the class of 

The most suitable indicator to be used when reacting ethanedioic acid with potassium hydroxide is