Acids and Bases

What is methyl orange’s colour in acid and base?

• Acid – blue; Base – green.

• Acid – red; Base – yellow.

• Acid – yellow; Base – blue.

• Acid – green; Base – red.

How is washing soda obtained?

• By recrystallization of sodium carbonate.

• By evaporation of seawater.

• By mixing sodium bicarbonate with vinegar.

• By heating sodium chloride with calcium carbonate.

What is the chemical name of baking soda?

• Sodium bicarbonate (NaHCO₃)

• Sodium hydrogen carbonate (NaHCO₃)

• Potassium bicarbonate (KHCO₃)

• Calcium carbonate (CaCO₃)

What is the use of common salt in food?

• As a preservative and to enhance taste.

• To add color to the food.

• To increase the nutritional value of the food.

• To make food more acidic.

What happens when CuSO₄·5H₂O is heated?

• It decomposes into CuSO₄ and H₂O.

• Loses water, becomes white anhydrous CuSO₄.

• It turns into a gas.

• It remains unchanged.

How is POP obtained?

• By heating gypsum (CaSO₄·2H₂O) to 373 K.

• By mixing calcium carbonate with water.

• By cooling plaster of Paris to room temperature.

• By adding sulfuric acid to calcium sulfate.

Why should POP be stored in airtight containers?

• To prevent it from absorbing moisture and hardening prematurely.

• To enhance its flavor and aroma.

• To increase its shelf life indefinitely.

• To make it easier to mix with other substances.

What is the use of chlorine gas released in this process?

• To prepare bleaching powder.

• To purify drinking water.

• To produce hydrochloric acid.

• To disinfect swimming pools.

What is the chemical formula of ammonium chloride?

• NH₄Cl

• NaCl

• KCl

• CaCl₂

What is the role of hydrogen gas formed in the process?

• Used as fuel or in ammonia synthesis.

• Used as a coolant in nuclear reactors.

• Used to purify water in filtration systems.

• Used as a propellant in rocket engines.