Analytical Chemistry Using Alkali Quiz

chromate ion is yellow
dichromate is orange
permanganate is purple or violet

Zinc(II)nitrate should be colorless because zinc ions do not have any unpaired electrons in their d orbitals, which means they do not absorb visible light and do not exhibit any color. In contrast, iron(II)sulphate, copper(II)sulphate, and iron(III)chloride contain transition metal ions that have unpaired electrons and can absorb certain wavelengths of light, resulting in colored solutions.

among the above mentioned ions ferric ion is yellow or brown in colour

When excess ammonium hydroxide solution is added to Copper(II)nitrate, it forms a deep inky blue solution. This is because the copper(II) ions in the salt react with the ammonium hydroxide to form a complex ion called tetraamminecopper(II) ion, which has a deep blue color. This reaction is specific to copper(II) ions and is used as a test for the presence of copper(II) ions in a solution.

Copper hydroxide will turn black on heating because it undergoes thermal decomposition, resulting in the formation of copper oxide and water. The black color is due to the formation of copper oxide, which is a black solid.

PbO is the correct answer because it is a yellow monoxide that dissolves in hot and concentrated caustic alkali. The other options, ZnO, Al2O3, and CuO, do not meet the criteria mentioned in the question.

The white gelatinous precipitate that appears when dilute ammonia solution is added to the colorless solution of a salt is a characteristic reaction of zinc salts. This precipitate is zinc hydroxide, which is insoluble in water. However, when excess ammonia solution is added, it forms a soluble complex with zinc, resulting in the dissolution of the precipitate. Therefore, the metal salt solution used in this case is likely a zinc salt.

Aluminium hydroxide and Lead(II)hydroxide are two bases that are not alkali but can dissolve in excess alkali. This means that when they are added to an excess of alkali solution, they will react and form soluble compounds. Alkalis are typically bases that are soluble in water, but these two bases are exceptions to that rule. They can still react with alkali solutions, but they do not themselves dissolve readily in water.

Aluminium oxide, Zinc oxide, and Lead(II) oxide all act as amphoteric oxides. This means that they can react as both an acid and a base. They can react with both acids and bases to form salts. Copper(II) oxide, on the other hand, is a basic oxide and does not have amphoteric properties. Therefore, the correct answer is I, II, and IV.

Silver chloride is the correct answer because it is the only chloride of metal that dissolves in excess of ammonium hydroxide. Lead(II) chloride, copper(II) chloride, and sodium chloride do not dissolve in excess of ammonium hydroxide.