Science Olympiad Test: Chemical Reactions and Equations- 1 - Class 10 MCQ

Combustion of LPG (a mixture of propane (C₃H₈), butane (C₄ H₁₀) etc. in liquified form) involves a chemical reaction.

Ferrous sulphate crystals initially lose water of crystallization. Then on strong heating evolve SO₂ ​and SO₃​.

So, O₂ is not involved.

When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

Here, oxygen combines with water to get oxidized. Oxygen is removed from water hence, it is getting reduced. Water is providing oxygen and it acts as an oxidizing agent.

• On introducing two molecules to each other, one molecule loses an electron. This reaction is called oxidation.
• On introducing two molecules to each other, one molecule gains an electron. This reaction is called reduction.
• The oxidized substance is called a reduction agent. The reduced substance is called an oxidizing agent.

Galvanisation is the process of coating iron with zinc in order to prevent its rusting.

Nitrogen and helium are inert gases and prevent the oxidation of oil and hence prevent the rancidity.

Different metals have different reactivity with acids. Aluminium reacts with dilute hydrochloric acid to give Aluminium chloride and hydrogen. Copper, gold and silver does not react with acids at all.

Rancidity is a very general term and in its most general meaning, it refers to the spoilage of food in such a way that it becomes undesirable for consumption. Food turns rancid when the fats and oils within them get oxidized and the taste and smell of the food change due to this reason.

Respiration is the process in which the cells of an organism obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP (energy).

In this reaction, potassium permanganate (KMnO4) is an oxidizing agent. It oxidises ferrous sulphate to ferric sulphate in the presence of dilute H₂SO₄.
2KMNO₄ + 10FeSO₄ + 8H₂SO₄ → K₂SO₄ + 2MnSO₄ + 5Fe(SO₄)₃ + 8H₂O
The solution is coloured purple because of the KMnO4 and it eventually disappears when all the KMnO4 in the solution is utilized.