Class 10 Science Chapter 2 Practice Question Answers - Acids, Bases and Salts

Fill in the Blanks
Q1: An acid turns blue litmus paper _____.
Ans: An acid turns blue litmus paper red. This change in color indicates the presence of acidic properties in the substance.

Q2: The chemical formula for sulfuric acid is _____.
Ans: The chemical formula for sulfuric acid is H2SO4. It is a strong diprotic acid commonly used in industrial processes.

Q3: Bases that are soluble in water are called _____.
Ans: Bases that are soluble in water are called alkalis. Alkalis are hydroxides of alkali metals and alkaline earth metals that readily dissolve in water to produce hydroxide ions (OH-) responsible for their basic nature.

Q4: The reaction between an acid and a base is called _____.
Ans: The reaction between an acid and a base is called neutralization. In this reaction, an acid reacts with a base to form salt and water, effectively neutralizing their acidic and basic properties.

Q6: Litmus solution is _____.
Ans: Litmus solution is a natural indicator. It is extracted from lichens and changes color to indicate the acidic or basic nature of a solution.

Short Answer Questions
Q6: Define pH scale.
Ans: The pH scale is a measure of the acidity or basicity of a solution. It ranges from 0 to 14, with 7 being neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity.

Q7: Give an example of a strong acid and a weak acid.
Ans: Hydrochloric acid (HCl) is an example of a strong acid, while acetic acid (CH3COOH) is an example of a weak acid.

Q8: What is the role of indicators in acid-base titrations?
Ans: Indicators are substances that change color to indicate the pH of a solution. In acid-base titrations, indicators help detect the endpoint of the reaction, where the amount of acid and base are stoichiometrically equivalent.

Q9: Write a balanced chemical equation for the reaction between an acid and a metal.
Ans: Acid + Metal → Salt + Hydrogen gas. For example, 2HCl + Zn → ZnCl2 + H2.

Q10: How do antacids provide relief from acidity?
Ans: Antacids are basic substances that neutralize excess stomach acid. They react with stomach acid, forming salt and water, thus reducing the acidic environment and providing relief from acidity.

Long Answers Questions
Q11: Explain the difference between acids and bases based on their chemical properties.
Ans: Acids are substances that release hydrogen ions (H+) when dissolved in water. They turn blue litmus paper red, have a sour taste, and react with metals to release hydrogen gas. Bases, on the other hand, release hydroxide ions (OH-) in water. They turn red litmus paper blue, have a bitter taste, and feel slippery. Acids and bases neutralize each other to form salt and water.

Q12: Describe the process of neutralization with an example.
Ans: Neutralization is a chemical reaction between an acid and a base, resulting in the formation of salt and water. For instance, when hydrochloric acid reacts with sodium hydroxide, sodium chloride (salt) and water are produced: HCl + NaOH → NaCl + H2O.

Q13: Explain the concept of the pH scale and its significance.
Ans: The pH scale measures the concentration of hydrogen ions in a solution. Lower pH values indicate higher acidity, higher pH values indicate alkalinity, and pH 7 is neutral. The scale is logarithmic, meaning each unit change represents a tenfold difference in hydrogen ion concentration. It's crucial for understanding the acidic or basic nature of substances and their impact on living organisms.

Q14: How are salts formed? Provide an example.
Ans: Salts are formed through the neutralization reaction between acids and bases. The hydrogen ions from the acid combine with the hydroxide ions from the base to form water, while the remaining ions combine to create the salt. For example, the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) produces sodium chloride (NaCl) and water (H2O).

Q15: Explain the importance of pH regulation in everyday life.
Ans: pH regulation is crucial for various processes in everyday life. In the body, maintaining the correct pH is essential for enzymatic activity, cellular function, and overall health. In agriculture, soil pH affects plant growth and nutrient availability. Industries control pH to optimize processes, such as in water treatment. pH regulation ensures optimal conditions for biological and chemical systems to function efficiently.