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- Practical Chemistry
NEET · Chemistry · Practical Chemistry
Consider the following statements regarding the preliminary tests...
Consider the following statements regarding the preliminary tests of anions with dilute :
I. A carbonate salt gives a colourless and odourless gas that turns lime water milky.
II. A sulphide salt evolves a gas with a pungent smell of burning sulphur.
III. A sulphite salt evolves a gas that turns acidified potassium dichromate paper green.
IV. A nitrite salt yields a colourless gas which turns into reddish-brown fumes on contact with air.
How many of the above statements are correct?
I. A carbonate salt gives a colourless and odourless gas that turns lime water milky.
II. A sulphide salt evolves a gas with a pungent smell of burning sulphur.
III. A sulphite salt evolves a gas that turns acidified potassium dichromate paper green.
IV. A nitrite salt yields a colourless gas which turns into reddish-brown fumes on contact with air.
How many of the above statements are correct?
Options
- AOne
- BTwo
- CFour
- DThree
Correct answer
D. Three
Step-by-step solution
Statement I is correct: Carbonate salts react with dilute to evolve gas, which is colourless, odourless, and turns lime water milky.
Statement II is incorrect: Sulphide salts evolve gas, which has a characteristic smell of rotten eggs. The pungent smell of burning sulphur is a characteristic of gas (evolved from sulphites).
Statement III is correct: Sulphite salts evolve gas, which is a reducing agent and turns acidified potassium dichromate paper green due to the formation of ions.
Statement IV is correct: Nitrite salts react with dilute acids to yield nitric oxide (), which is colourless but rapidly oxidises in air to form reddish-brown fumes of nitrogen dioxide ().
Therefore, three statements (I, III, and IV) are correct.
Answer: Three
Statement II is incorrect: Sulphide salts evolve gas, which has a characteristic smell of rotten eggs. The pungent smell of burning sulphur is a characteristic of gas (evolved from sulphites).
Statement III is correct: Sulphite salts evolve gas, which is a reducing agent and turns acidified potassium dichromate paper green due to the formation of ions.
Statement IV is correct: Nitrite salts react with dilute acids to yield nitric oxide (), which is colourless but rapidly oxidises in air to form reddish-brown fumes of nitrogen dioxide ().
Therefore, three statements (I, III, and IV) are correct.
Answer: Three