Arrange the following oxyacids of chlorine in decreasing order of their thermal stability. Give reason. HOClO 3 , HOCl , HClO 4 , HOClO 2

With the decrease in oxidation state of chlorine, the oxidising power of its oxoacids increases and the thermal stability of oxoacids of chlorine decreases. Thus, the decreasing order of thermal stability is: HClO 4 > HOClO 3 > HOCl 2 > HOClO

Explain the following with the help of balanced chemical equation: Dehydration of formic acid by concentrated H 2 SO 4

Concentrated H 2 SO 4 is a strong dehydrating agent due to its affinity for water. Reaction: HCOOH → Conc . H 2 SO 4 CO + H 2 O

Explain the following with the help of balanced chemical equation: Bleaching action of SO 2

SO 2 is used as a bleaching agent in presence of moisture. Bleaching takes place due to reduction and it is temporary. Reaction: SO 2 + 2 H 2 O → H 2 SO 4 + 2 ( H )

Write any ‘four points’ of difference between fluorine and other halogens.

Fluorine Other halogens It is more reactive due to its smaller atomic size and low F-F bond dissociation energy. Other halogens are less reactive than fluorine. Fluorine Other halogens Hydrogen bonding is present in hydrides of fluorine. Hydrogen bonding is not present in their hydrides. Fluorine Other halogens It shows -1 oxidation state in all compounds. They show variable oxidation states. Fluorine Other halogens Due to absence of vacant d-orbital, it does not form any polyhalide ion. They form poly halide ion.

Write structure and molecular formula for the following compounds: sulphurous acid

Sulphurous acid appears as a colourless liquid with a pungent burning sulphur odour. It is corrosive to metals and tissue. Formula of sulphurous acid: This inorganic oxy- acid contains hydrogen radical and sulphite radical. The valency of hydrogen radical ( H + ) is one and sulphite radical ( SO 3 2 - ) is two. After criss-crossing the valency numbers, the formula can be written as H 2 SO 3 . Molecular formula: H 2 SO 3 Structure: