Acid, Base and Salts RRB PYQ

When dry slaked lime (calcium hydroxide) reacts with chlorine, calcium oxychloride (bleaching powder) is formed as the main product. The chemical reaction is: Ca(OH)2(s) + Cl2(g) → CaOCl2 + H2O. Calcium oxychloride is widely used for disinfecting drinking water, bleaching textiles and paper, and as an oxidizing agent in various industries.

Hydrochloric acid (HCl) reacts with water (H2O) to liberate H3O+ (hydronium ion) and Cl- (chloride ion). Hydronium ion is formed when a water molecule combines with the hydrogen ion (H+) from HCl. Chloride ion is left after HCl dissociates.

pH is a measure of the concentration of hydrogen ions (H+) in a solution. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration: pH = -log10[H+], where [H+] represents the hydrogen ion concentration in moles per liter (M). In this case, the hydrogen ion concentration is given as 1×10^-5 M. Substituting this value into the formula, we get: pH = -log10(1×10^-5) = 5. Therefore, the pH of the solution is approximately 5.

The reaction HNO3(aq) + KOH(aq) → KNO3(aq) + H2O(l) is an example of a neutralisation reaction, where an acid (nitric acid, HNO3) reacts with a base (potassium hydroxide, KOH) to form a salt (potassium nitrate, KNO3) and water.

Statement I is incorrect because anhydrous sodium carbonate is not used in soda-acid fire extinguishers; sodium bicarbonate (baking soda) is used instead. Statement II is correct as anhydrous sodium carbonate is dissolved in water and recrystallized to produce washing soda crystals (sodium carbonate decahydrate) containing 10 molecules of water of crystallization.

When chlorine reacts with dry slaked lime, bleaching powder (CaOCl2) is formed. The chemical reaction is given as: Cl2 + Ca(OH)2 → CaOCl2 + H2O. Calcium Oxychloride is bleaching powder, which is generally used as a disinfectant and bleaching agent.

Since blue litmus paper turns red in an acidic solution, the solution that turns blue litmus paper red is likely to be acidic. Therefore, the pH of the solution would be less than 7. Among the given options, 6 is the closest value below 7, making it the most likely answer. While the exact pH might not be precisely 6, it falls within the acidic range (less than 7) based on the litmus paper test.

In the chlor-alkali process, 'chlor' represents chlorine gas, while 'alkali' refers to sodium hydroxide (NaOH). This process involves electrolyzing a sodium chloride (brine) solution, which results in the production of chlorine gas and sodium hydroxide as a byproduct. Sodium hydroxide is a white, crystalline solid that is a strong alkali used in various chemical applications.

Calcium sulphate dihydrate is the chemical name for Gypsum. Gypsum is widely used in industries such as construction for making plaster and drywall due to its fire-resistant properties. In agriculture, it improves soil structure, and in the food industry, it serves as a coagulant for tofu and as a calcium supplement.

Salt and water are produced when acid and base react. Hydrogen gas is liberated when acids react with metals. When an acid reacts with a base, a neutralisation reaction occurs. This reaction has different applications, such as antacid medications, water treatment, and soil pH balance.