An amorphous solid "A"bums in air to form a gas "B"which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4 solution and reduces Fe3+ to Fe+2. Identify the solid "A"and the gas "B"and write the reactions involved.
A is sulphur (Sg) while B is sulphur dioxide (SO2).

Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.
Explain why inspite of nearly the same electronegativity, nitrogen forms hydrogen bonding while chlorine does not.
Why is BiH3 the strongest reducing agent amongst all the hydrides of group 15 elements? (C.B.S.E. 2013)
Explain why does the stability of oxoacids of chlorine increase in the order given below:
HClO < HClO2 < HClO3 < HClO4
Match the compounds given in Column I with the hybridization and shape given in Column II and mark the correct option.

How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions . involved.
Justify the placement of O, S, Se, Te and Po in the same group’of the periodic table in terms of electronic configuration, oxidation state and hydride formation.
Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidizing power.

In the preparation of H2S06 by contact process, why is S03 not absorbed directly in water to form H2S04?
Write a balanced chemical equation, for the reaction showing catalytic oxidation of NH3 by atmospheric oxygen.
Phosphorus forms a number of oxoacids. Out of these oxoacids phosphinic acid has strong reducing property. Write its structure and also write a reaction showing its reducing behaviour.
Assertion (A): HNO3 makes from passive.
Reason (R): HNO3 forms a protective layer of ferric nitrate on the surface of iron.
What happens when sulp’hur dioxide is passed through an aqueous solution of Fe(III) salt?
Why does nitrogen show catenation properties less than phosphorus ? (C.B.S.E. Foreign 2009)
How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions . involved.
An amorphous solid "A"bums in air to form a gas "B"which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4 solution and reduces Fe3+ to Fe+2. Identify the solid "A"and the gas "B"and write the reactions involved.
What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO2?