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प्रश्न
You are provided with two reagent bottles marked A and B. One of which contains NH4OH solution and the other contains NaOH solution. How will you identify them by a chemical test?
उत्तर
Reagent bottles A and B can identified by using calcium salts such as Ca(NO3)2.
When NaOH is added to Ca(NO3)2, Ca(OH)2 precipitates as a white precipitate that is sparingly soluble in excess of NaOH.
\[\ce{Ca(NO3)2 + 2NaOH -> Ca(OH)2 + 2NaNO3}\]
whereas, on addition of NH4OH to calcium salts, no precipitation of Ca(OH)2 occurs even with an excess of NH4OH because the concentration of OH−ions from the ionization of NH4OH is so low that it cannot precipitate the calcium hydroxide.
So the reagent bottle which gives white precipitate is NaOH and the other is NH4OH.
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संबंधित प्रश्न
Match the following :
| Column A | Column B |
| 1. A substance that turns moist starch iodide paper blue. |
A. Ammonium sulphate |
| 2. A compound which releases a reddish brown gas on reaction with concentrated sulphuric acid and copper turnings. |
B. Lead carbonate |
| 3 . A solu tion of this compound gives a dirty green preci pi ta te with sodium hydroxide. |
C. Chlorine |
| 4 . A compound which on heating with sodium hydroxide produces a gas which forms dense white fumes with hydrogen chloride. |
D. Copper nitrate |
| 5 . A white solid which gives a yellow residue on heating. |
E. Ferrous sulphate |
Identify the substance P based on the information given below:
The deliquescent salt P, turns yellow on dissolving in water, and gives a reddish brown precipitate with sodium hydroxide solution.
Identify the substance Q based on the information given below:
The pale green solid 'R' turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.
Choose the correct answer from the options given below :
When dilute sulphuric acid reacts with iron sulphide, the gas evolved is _______
Sodium hydroxide solution is added first in a small quantity, then in excess to the aqueous salt solution of copper (II) sulphate, zinc nitrate, lead nitrate, calcium chloride and iron (III) sulphate. Copy of the following table and write the colour of the precipitate in (i) to (v) and the nature of the precipitate (soluble or insoluble) in (vi) to (x).
|
Aqueous salt solution |
Colour of the precipitate when NaOH is added in small quantity |
Nature of the(soluble or insoluble) when NaOH is added in excess |
|
copper (II) sulphate zinc nitrate lead nitrate calcium chloride Iron (III) sulphate |
(i) (ii) (iii) (iv) (v) |
(vi) (vii) (viii) (ix) (x) |
Write balanced equation for a metal that evolves a gas which burns with a pop sound when boiled with alkali solutions.
Write balanced equation for a coloured metallic oxide which dissolves in alkalis to yield colourless solutions.
Write balanced equations for a coloured metallic oxide which dissolves in alkalis to yield colourless solutions.
Write balanced equation for a coloured metallic oxide which dissolves in alkalis to yield colourless solutions.
Write balanced equation for a metal that evolves a gas which burns with a pop sound when boiled with alkali solutions.
