Common Chemical Compounds and Reactions

KNaCO3 (potassium sodium carbonate) is a double salt. Double salts are compounds that contain two different cations that crystallize together in a fixed ratio. The other options are simple single-cation salts.

Plaster of Paris is calcium sulfate hemihydrate, represented as CaSO4·1/2H2O, meaning each calcium sulfate unit is associated with half a water molecule. It's produced by heating gypsum (CaSO4·2H2O) to about 150°C, which drives off about 1.5 water molecules per unit. When mixed with water, it rehydrates to form gypsum, creating a hard solid - the basis for casts and molds.

Soaps are produced through saponification - the reaction between fats/triglycerides and strong alkalis like sodium hydroxide (NaOH) or potassium hydroxide (KOH). This process produces glycerol and soap salts. The other options are incorrect because alcohols, acids, or water alone cannot convert fats into soap.

Na2CO3.10H2O is the correct formula for washing soda (sodium carbonate decahydrate). This is different from soda ash (anhydrous Na2CO3) or the monohydrate form. The 10 water molecules are chemically bound in the crystal structure, which gives washing soda its characteristic properties.

In zeolite water softening, sodium ions (Na+) from the zeolite exchange with calcium and magnesium ions (Ca2+, Mg2+) in hard water. The zeolite releases Na+ and traps Ca2+/Mg2+ ions. This process removes hardness ions that cause scaling. Option B correctly identifies Na+ and Mg2+ as involved in the exchange.

Gypsum (calcium sulfate dihydrate) is added to clinker during the manufacturing of Portland cement to control the setting time. Without gypsum, the cement would react with water and set almost immediately, preventing proper mixing and placement.

Sodium thiosulphate forms strong complex with gold ions and it is non-toxic. So, some very refractory substances in gold ore can be leached.

Sodium oxide is not present in cement at all.

This method is used for manufacturing sodium cabonate.

Sulphur dioxide is affecting the Taj in the form of acid rain.

Crookes glass (or Crookes radiometer glass) contains cesium oxide, which gives it its distinctive yellow color and radiation-absorbing properties. It was historically used in radiology for X-ray protection.

Nitric acid is sometimes referred to as 'Aqua Fortis' in historical and industrial contexts. The term 'Aqua Gold' appears to be a confusion between 'Aqua Fortis' (strong water - nitric acid) and 'Aqua Regia' (royal water - mixture of nitric and hydrochloric acids that can dissolve gold). Among the options, nitric acid is the closest match.

Bone char is often used in sugar refining as a decolourising and deashing agent.

In glass manufacturing, soda ash (sodium carbonate) serves multiple crucial functions. One of its primary roles is to act as a flux that helps remove air bubbles from the molten glass, ensuring clarity and structural integrity. It lowers the melting temperature of silica and helps eliminate gaseous impurities that would otherwise create defects.