MEDIUM
8th CBSE
IMPORTANT
Earn 100
When copper metal is subjected to treatment with nitric acid, different oxides of nitrogen are liberated with different concentrations of nitric acid. Explain the reason.
Important Questions on Some Important Elements and their Compounds
HARD
8th CBSE
IMPORTANT
Ammonium chloride on reaction with quick lime gives a gas X which turns red litmus blue. Excess of X and greenish yellow gas are taken in container A and excess of greenish-yellow gas and X are taken in container B which on reaction gives different sets of products. When moist litmus paper is introduced into the jars, it turned to red in jar B. Identify the reactions involved and give equations.
HARD
8th CBSE
IMPORTANT
Hydrogen chloride gas can be subjected to drying only with conc. but not with quick lime or phosphorus pentoxide. Explain.
MEDIUM
8th CBSE
IMPORTANT
Why are soaps ineffective during usage with hard water which contains soluble salts of calcium and magnesium?
HARD
8th CBSE
IMPORTANT
When a binary salt of iron reacts with hydrochloric acid, it gives out a gas which can be used for identification of many metal ions. Identify the salt, the gas and explain how it is useful in detecting metal ions.
MEDIUM
8th CBSE
IMPORTANT
Nitric acid is colourless when freshly prepared. But, on long-standing, it turns to yellow. How do you account for this?
MEDIUM
8th CBSE
IMPORTANT
Two research scholars Rony and Jony, needed red phosphorus and white phosphorus, respectively, for a research program. Both of them went to a chemical store to purchase red phosphorus and white phosphorus. The storekeeper gave a normal glass bottle containing red phosphorus and a glass bottle containing white phosphorus which was kept in water. Justify the above observations.
HARD
8th CBSE
IMPORTANT
A solid non-metal A on exposure to air forms a compound B which on dissolution in water forms the highest oxyacid C. Identify different types of salt which can be formed when C reacts with caustic potash.
MEDIUM
8th CBSE
IMPORTANT
Though is a very good desiccant, its utility for drying is limited. Give reasons.
