Acids, Bases and Salts

Acids in food are referred to as food acids. Which of the following foods contains ascorbic acid?

• 
• 
• 
• 

Answer explanation

Ascorbic acid is present in oranges.

Lemon, apple, and black tea contain citric acid, malic acid, and tannic acid, respectively.

Which formula represents nitric acid?

• H₂SO₄

• HCl

• HNO₃

• H₃NO

Answer explanation

Nitric acid is represented by the formula HNO₃. The other options correspond to different acids: H₂SO₄ is sulfuric acid, HCl is hydrochloric acid, and H₃NO is not a standard formula for any common acid.

Dilute acids react with metal carbonates to form a salt, water and ______ _______ gas.

(a)  

Answer explanation

Dilute acids react with metal carbonates to produce a salt, water, and carbon dioxide gas. The release of carbon dioxide is a characteristic reaction when acids interact with carbonates.

Which gas is produced when dilute acids react with most metals?

• Oxygen

• Carbon dioxide

• Hydrogen

• Nitrogen

Answer explanation

When dilute acids react with most metals, they produce hydrogen gas as a byproduct. This is a common reaction in chemistry, making hydrogen the correct answer.

Which of the following consists of bases only?

• Copper oxide, Copper(II) sulfate, Hydrochloric acid

• Ammonium hydroxide, Calcium oxide, Sodium hydroxide

• Potassium hydroxide, Sodium oxide, Sodium chloride

• Magnesium oxide, Sulfuric acid, Zinc oxide

Answer explanation

The correct choice is Ammonium hydroxide, Calcium oxide, Sodium hydroxide, as all three are bases. The other options contain acids or salts, which do not consist of bases only.

Which of the pairs of reagents can be used for a neutralisation reaction?

• Magnesium + Hydrochloric acid

• Hydrogen + Oxygen

• Potassium hydroxide + Sulfuric acid

• Zinc + Nitric acid

Answer explanation

The reaction between an acid and a base that produces a salt and water is known as a neutralisation reaction.

Potassium hydroxide (base) reacts with sulfuric acid (acid) to produce potassium sulfate and water.

Which of the following statement is correct according to the pH scale?

• Bleach is more acidic than Soap

• Milk is more acidic than Tomato juice

• Apple juice is less acidic than Lemon juice

• Baking soda is less basic than egg

Answer explanation

Apple juice has a higher pH (less acidic) than lemon juice, which is more acidic. The other statements are incorrect based on the pH scale, making this the only correct choice.

The identity of an unknown solution is being determined using litmus paper. Based on the colour change of the litmus paper, what does the solution contain?

• Sodium hydroxide

• Sodium chloride

• Copper (II) sulfate

• Nitric acid

Answer explanation

The litmus paper turns red in the presence of an acid. Since nitric acid is an acid, it will cause the litmus paper to change color to red, indicating the solution contains nitric acid.

Liming is the process of adding _______ _________ to soil to restore its pH.

• Potassium hydroxide

• Magnesium hydroxide

• Ammonium hydroxide

• Calcium hydroxide

Answer explanation

Liming involves adding Calcium hydroxide to soil, which helps neutralize acidity and restore optimal pH levels for plant growth. Other options like potassium, magnesium, and ammonium hydroxides do not serve this specific purpose.

Which of the following can be used to treat the sting caused by the insect shown?

• Vinegar

• Calcium hydroxide

• Sodium bicarbonate

• Baking soda

Answer explanation

Bee stings are acidic and can be treated with baking soda.