Chemical Compounds and Reactions

This option is correct because formic acid and Fehling solution react to produce cuprous oxide, which gives reddish brown precipitate.

This option is correct because acetanilide are formed by the aniline due to the addition of zinc, this reduces the coloured impurities of the aniline and also prevents the oxidation of the reaction.

Ans : 4.

Copper sulphate is blue in colour because it has been oxidised to the Cu2+ ion which is a d-block metal ion.

This is the correct option. The crystals of copper sulphate are blue in colour due to the water of crystallisation. 

Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu₂O. It is one of the principal oxides of copper. This red-coloured solid is a component of antifouling paints.

Bismuth(III) oxide is found naturally as a mineral bismite and sphaerobismoite but it is usually obtained as a by-product of the smelting of copper and lead ores. Bismuth trioxide is commonly used to produce the Dragon's eggs effect in fireworks, as a replacement of red lead.

It is lithium salt of nitric acid. It is made by reacting lithium carbonate or lithium hydroxide with nitric acid.This deliquescent colourless salt is an oxidizing agent used in the manufacture of red-coloured fireworks and flares.

Potassium permanganate is an inorganic chemical compound with the formula KMnO₄. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the evaporation of which leaves prismatic purplish-black glistening crystals.

Radium chloride is a white solid with a blue-green luminescence, especially when heated. It is less soluble in water than other alkaline earth metal chlorides. It is still used in the initial stages of the separation of radium from barium during the extraction of radium from pitchblende.

Cyanuric fluoride or 2,4,6-trifluoro-1,3,5-triazine is a colourless, pungent liquid. It has been used as a precursor for fibre-reactive dyes, as a specific reagent for tyrosine residues in enzymes, and as a fluorinating agent.

Potassium ferricyanide is the chemical compound with the formula K₃[Fe(CN)₆]. This bright red salt contains the octahedrally coordinated [Fe(CN)₆]³⁻ ion. The compound has widespread use in blueprint drawing and in photography (Cyanotype process). Potassium ferricyanide is used as an oxidizing agent to remove silver from negatives and positives, a process called dot etching.

AgNO3 is silver nitrate, used in photography and medicine. Silver phosphate would be Ag3PO4, silver chloride is AgCl, and none of these is incorrect since B is right.

White vitriol is the historical name for zinc sulfate heptahydrate (ZnSO₄·7H₂O). The 'vitriol' name comes from vitriolum (sulfate salts). Different vitriols are distinguished by color - blue vitriol (copper sulfate), green vitriol (iron(II) sulfate), white vitriol (zinc sulfate), and Epsom salt (magnesium sulfate).

Potassium sodium tartrate is a colourless to blue-white salt crystallizing in the orthorhombic system. It has a specific gravity of about 1.79, a melting point of approximately 75 °C, and has a saline, cooling taste. It has been used medicinally as a laxative. It has also been used in the process of silvering mirrors.