Common Chemical Compounds and Reactions

Starch solution (colloid) will show Tyndall effect. The Tyndall effect is light scattering by particles in a colloid or particles in a fine suspension.

Permanent hardness of water is caused by the presence of dissolved chlorides and sulphates of calcium and magnesium. Calcium sulphate is a primary contributor to this condition, which cannot be removed by simple boiling. In contrast, bicarbonates cause temporary hardness.

This is the correct option. Ammonium hydroxide is found in window cleaner solution and has a chemical formula NH₄OH. Magnesium hydroxide is found in milk of magnesia and has a chemical formula Mg(OH)₂. Calcium hydroxide is found in limewater and has a chemical formula Ca(OH)₂. Potassium hydroxide is found in liquid soap and has a chemical formula KOH.

Bauxite is the primary ore of aluminium and is chemically a mixture of hydrated aluminium oxides, typically Al2O3.nH2O.

Water that contains mineral salts (as calcium and magnesium ions) that limit the formation of lather with soap called hard water. Such water contains metal ions (calcium, magnesium, iron) which, instead of lather form precipitate with soap. The rain water dissolves sulphates, chlorides and carbonates of calcium and magnesium present in many rocks. These salts cause hardness of water. This water also dissolves carbon dioxide from air which converts the carbonates of calcium and magnesium into bicarbonates. These bicarbonates being soluble in water cause hardness. The hardness of water is of two types:- temporary hardness and permanent hardness. Temporary hardness is due to the presence of bicarbonates of calcium and magnesium in water. These salts are soluble in water and exist in the form of positive and negative ions. The name temporary is given to this type of hardness because these ions are removed merely by boiling. Temporary hardness is removed by boiling water. Due to this calcium and magnesium bicarbonates are converted into insoluble carbonates witch are easily removed. Permanent hardness is due to the dissolved chlorides or sulphates of calcium and magnesium. These salts can not be decomposed by boiling and hence the name permanent is given to this type of hardness. These salts are soluble in water and produce corresponding ions in solution. Both temporary and permanent hardness can also be removed by ion exchange method which involves the replacement of one ion by another.

Temporary hardness of the water is due to the presence of calcium bicarbonate. Water's hardness is determined by the concentration of multivalent cations in the water. Multivalent cations are cations (positively charged metal complexes) with a charge greater than 1⁺. Usually, the cations have the charge of 2⁺. Common cations found in hard water include Ca²⁺ and Mg²⁺.

EDTA is used for enlargement of the calcified canals.

Sodium hypochlorite (NaClO) is the active ingredient in household bleach, responsible for its disinfecting and whitening properties.

Household bleach is a solution of sodium hypochlorite (NaClO). Sodium chloride is table salt, and sodium hydroxide is lye.

When the saturated solution of magnesium chloride is made to react with magnesium oxide, the resulting paste is a hard marble like mass forming MgCl₂.5MgO.xH₂O. Hence, this option is correct.

This option is correct because on heating orthophosphoric acid at 250⁰C, it loses a water molecule and forms polyphosphoric acid. It is further heated at 500⁰C to lose another molecule of water and form metaphosphoric acid. it is a glassy solid salt.

This option is correct because sodium hypochlorite is well known disinfectant and sterilizing agent and used extremely in bleaching cotton fibres.

Tollens reagent is a chemical reagent used to detect aldehydes, consisting of a solution of silver nitrate and ammonia.

Saltpetre is the common name for potassium nitrate (KNO3). It has historically been used in fertilizers, gunpowder, and food preservation.

Epsom salt is the common name for magnesium sulfate heptahydrate (MgSO4·7H2O). It is widely used for baths and as a fertilizer.