Chemistry
Which of the following is the best reagent to distinguish lead nitrate and zinc nitrate ?
P NaOH solution
Q KOH solution
R NH4OH solution
Only P
Only R
Only Q
Both P and Q
Analytical Chemistry
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Answer
Only R
Reason
- With NaOH (P) or KOH (Q), both lead nitrate and zinc nitrate give a white precipitate that dissolves in excess alkali, so they cannot be distinguished.
- With NH₄OH (R):
- Lead nitrate gives a white precipitate insoluble in excess NH₄OH.
- Zinc nitrate gives a white precipitate soluble in excess NH₄OH (forms a soluble complex).
Hence, NH₄OH solution is the best reagent to distinguish between the two.
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Related Questions
A metal which produces hydrogen on reacting with alkali as well as with acid:
- Iron
- Magnesium
- Zinc
- Copper
The salt solution which does not react with ammonium hydroxide is:
- Calcium nitrate
- Zinc nitrate
- Lead nitrate
- Copper nitrate
A student takes Cu, Al, Fe and Zn strips, separately in four test tubes labeled as I, II, III and IV respectively. He adds 10 ml of freshly prepared ferrous sulphate solution to each test tube and observes the colour of the metal residue in each case.
He would observe a black residue in the test tubes:
- (I) and (II)
- (I) and (III)
- (II) and (III)
- (II) and (IV)
Assertion (A): Calcium salt solution does not show any change even after adding an excess of ammonia solution to it.
Reason (R): The low concentration of hydroxide ion in ammonium hydroxide solution which are unable to precipitate the hydroxide ions of calcium
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.