The rusting of iron is accelerated by: MCQ with Answer and Explanation

The rusting of iron is accelerated by:
A. Presence of salt in water
B. Dry air
C. Placing in vacuum
D. Coating with paint
Answer: Option A
Solution (By JKExamLibrary)
Salt (NaCl) dissolved in water increases the electrical conductivity of the electrolyte, facilitating the electrochemical corrosion process. This is why iron rusts faster in coastal areas and on roads treated with deicing salts. Dry air prevents rusting (needs moisture). Coating with paint blocks oxygen and moisture. Vacuum has no oxygen.

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Practice More chemistry Questions

Question #1
The main raw material for the manufacture of cement is:
A. Limestone and gypsum
B. Gypsum and sand
C. Limestone and clay
D. Sand and clay

Correct Answer: Option C


Explanation:
Portland cement is primarily made by heating a mixture of limestone (calcium carbonate) and clay (aluminosilicates) in a kiln at about 1450°C to form clinker. A small amount of gypsum is then added to the clinker to control the setting time, but limestone and clay are the main raw materials.

This question belongs to: Science chemistry
Question #2
The main constituent of cement is:
A. Magnesium oxide
B. Calcium carbonate
C. Silica only
D. Calcium silicate

Correct Answer: Option D


Explanation:
Portland cement primarily consists of calcium silicates (C₃S and C₂S) along with aluminates. These are formed by heating limestone and clay.

This question belongs to: Science chemistry
Question #3
Which of the following is an acidic salt?
A. NaHCO₃
B. Na₂CO₃
C. CaOCl₂
D. K₂SO₄

Correct Answer: Option A


Explanation:
Sodium bicarbonate (NaHCO₃) is an acidic salt because it contains a replaceable hydrogen atom (can neutralize bases). Its aqueous solution is mildly basic due to hydrolysis, but chemically it is an acid salt (formed by partial replacement of H of carbonic acid). K₂SO₄ is normal salt, CaOCl₂ is mixed salt, Na₂CO₃ is normal salt. Acid salts can react with bases.

This question belongs to: Science chemistry