Test: Acids, Bases & Salts - Class 7 MCQ

Vinegar is an acidic substance due to the presence of acetic acid.

Sulphuric acid is commonly used in car batteries as it is a strong acid and can provide high energy.

• Lemon juice is acidic, containing citric acid.
• Vinegar is also acidic, primarily due to acetic acid.
• Tomato juice is acidic, containing various acids like citric acid.
• Ammonia, on the other hand, is a basic substance. It has a pH greater than 7 and can accept protons, making it alkaline.

• Litmus: A natural dye derived from lichens that changes color based on acidity.
• Color Change: In acidic solutions, litmus turns red; in basic solutions, it turns blue.
• Usage: It is commonly used in laboratories to test pH levels quickly.
• Other Indicators: While phenolphthalein and methyl orange are also indicators, litmus is the most recognized for testing acidity.

Water is a neutral substance as it has a pH of 7 and does not show any acidic or basic properties.

Sodium chloride is a salt that is commonly used in cooking and food preservation.

Citric acid is a weak organic acid that is found in citrus fruits such as lemons and oranges.

Hydrochloric acid is a strong acid that is commonly used in industrial processes and laboratory experiments.

Sodium hydroxide is a strong base that is commonly used in cleaning products such as drain cleaners and oven cleaners.

Acetic acid is commonly used as a preservative in food products such as pickles and sauces.

Litmus is a natural dye that is used as an indicator for acidic and basic substances.

Magnesium hydroxide is commonly used in antacids as it can neutralize excess stomach acid.

Acetic acid is a weak acid that is found in vinegar and can be used for cooking and preservation.

Sodium hydroxide is a strong base that is commonly used in cleaning products and industrial processes.

Nitric acid is commonly used in the manufacture of fertilizers as it can provide essential nutrients to plants.

All three options—litmus, phenolphthalein, and methyl orange—are indicators that can detect basic (alkaline) substances. Litmus turns blue in bases, phenolphthalein turns pink in basic solutions, and methyl orange turns yellow in bases. Therefore, the correct answer is "All of the above."

Sodium hydroxide is commonly used in the production of soap as it can react with fats and oils to form soap.

Lactic acid is commonly found in milk and other dairy products and is responsible for their sour taste.

This is a neutralization reaction as the acid (HCl) and base (NaOH) react to form a salt (NaCl) and water (H₂O).

Sodium carbonate is commonly used in the production of glass as it can lower the melting point of glass and make it easier to work with.