CHEMISTRY CHAPTER 6 MCQ

What is the definition of an acid?

• A substance that neutralizes a base

• A substance that produces hydroxide ions in water

• A substance that forms salts

• A substance that produces hydrogen ions in water

Answer explanation

An acid is defined as a substance that produces hydrogen ions (H+) in water. This characteristic distinguishes acids from bases, which produce hydroxide ions (OH-). Therefore, the correct answer is the one that states this definition.

Which of the following is a strong acid?

• Acetic acid

• Hydrochloric acid

• Carbonic acid

• Citric acid

Answer explanation

Hydrochloric acid is a strong acid because it completely dissociates in water, releasing a high concentration of hydrogen ions. In contrast, acetic, carbonic, and citric acids are weak acids that do not fully dissociate.

What is the pH value of a neutral solution?

• 10

• 14

• 7

• 0

Answer explanation

The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity. Therefore, the pH value of a neutral solution is 7.

What is the role of water in showing acidic properties?

• It acts as a solvent for bases

• It forms salts with acids

• It helps in the dissociation of acids

• It neutralizes acids

Answer explanation

Water plays a crucial role in the dissociation of acids by breaking them down into ions, which is essential for exhibiting acidic properties. This process allows acids to release protons (H+), contributing to their acidity.

Which of the following is an example of an alkali?

• Calcium carbonate

• Sulfuric acid

• Potassium hydroxide

• Sodium chloride

Answer explanation

Potassium hydroxide is an alkali because it is a strong base that dissociates in water to produce hydroxide ions. In contrast, calcium carbonate is a salt, sulfuric acid is an acid, and sodium chloride is a neutral salt.

What does the term 'basicity' refer to?

• The solubility of a base

• The number of moles of H+ ions produced by an acid

• The strength of an acid

• The pH of a solution

Answer explanation

The term 'basicity' refers to the number of moles of H+ ions produced by an acid. It indicates how well an acid can donate protons, which is a key aspect of its strength.

What is the chemical equation for the neutralization of hydrochloric acid with sodium hydroxide?

• HCl + NaOH → Na2Cl + H2O

• HCl + NaOH → Na + Cl + H2O

• HCl + NaOH → H2 + NaCl

• HCl + NaOH → NaCl + H2O

Answer explanation

The correct equation for the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH) produces sodium chloride (NaCl) and water (H2O). Thus, HCl + NaOH → NaCl + H2O is the right choice.

What is the pH range for acidic solutions?

• 7 to 10

• 0 to 7

• 0 to 14

• 7 to 14

Answer explanation

The pH scale ranges from 0 to 14, where values below 7 indicate acidity. Therefore, the correct range for acidic solutions is 0 to 7.

Which of the following acids is used as a food preservative?

• Sulfuric acid

• Benzoic acid

• Nitric acid

• Hydrochloric acid

Answer explanation

Benzoic acid is commonly used as a food preservative due to its ability to inhibit the growth of mold, yeast, and some bacteria, making it effective in extending the shelf life of various food products.

What is the process of adding water to a concentrated solution called?

• Dilution

• Filtration

• Neutralization

• Evaporation

Answer explanation

The process of adding water to a concentrated solution is called dilution. This reduces the concentration of the solute in the solution, making it less concentrated.