Acid, Base and Salts RRB PYQ

The incorrect statement is that when pH of rain water is more than 5.6, it is called acid rain. Acid rain occurs when the pH of rainwater is less than 5.6 because of the presence of sulfur dioxide and nitrogen oxides in the atmosphere. These gases react with water vapor to form sulfuric acid and nitric acid. If the pH is more than 5.6, the rain is called a normal rain.

Bleaching powder is manufactured by the action of chlorine gas on dry slaked lime (calcium hydroxide). This process typically occurs in plants such as Hasenclever or Bachmann's plants. The chemical formula for bleaching powder is commonly represented as CaOCl2: Ca(OH)2 + Cl2 → CaOCl2 + H2O. Bleaching powder is used as an oxidiser in many chemical industries. When exposed to air, it reacts with carbon dioxide to release chlorine gas.

Litmus solution is derived from lichen, which belongs to the Thallophyta group of plants. This natural dye is commonly used to test whether a solution is acidic or basic. In distilled water, litmus has a purple color. When added to an acidic solution, it turns red, and in a basic solution, it turns blue.

The common name of the compound Ca(OCl)2 is Bleaching powder. This chemical is widely used as a bleaching agent and disinfectant. It is produced by reacting chlorine gas with calcium hydroxide. Bleaching powder is effective in removing stains and disinfecting water.

Gastric juice has the lowest pH value of 1 to 3. The pH scale tells how basic or acidic a substance is, ranging from 0 to 14. Lemon juice has a pH value of 2 to 3, while the values for blood and milk of magnesia are 7.35-7.45 and 10-11, respectively.

Onion extract is an olfactory indicator. These substances identify acids and bases through a change in smell/odour rather than colour. In acids, onion extract retains its characteristic pungent smell. In bases, the characteristic smell of onion disappears or becomes undetectable. Other olfactory indicators include vanilla essence and clove oil. Like onion, they lose their distinct smell in basic solutions but retain it in acidic ones.

NH4OH (ammonium hydroxide) is a weak base, meaning it does not fully dissociate in water and therefore produces fewer OH- ions compared to strong bases. Strong bases like Ba(OH)2, NaOH, and even the slightly less soluble Ca(OH)2 dissociate more completely, releasing more OH- ions in solution. NH4OH's partial dissociation results in a lower concentration of hydroxide ions in water.

The common name of baking soda is sodium bicarbonate, and its chemical formula is NaHCO3. Baking soda is a white crystalline powder that is slightly alkaline in nature. Apart from culinary uses, baking soda is also used in cleaning, neutralizing odors, and even in some medical applications such as relieving heartburn or indigestion due to its antacid properties.

Chlorine (Cl2) gas is used in the manufacture of Bleaching powder.

The chlor-alkali process electrolyzes saltwater (brine) to produce chlorine gas, hydrogen gas, and sodium hydroxide (NaOH). Chlorine is used in disinfectants and PVC production, hydrogen serves as a fuel and in ammonia synthesis, and NaOH is essential in soap making and paper production. This process is fundamental in the chemical industry, providing key materials for numerous applications.