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11. Which of the following are chemical changes? Growth of a plant b) Rusting of iron Mixing of iron filings and sand [d] Cooking of food le) Digestion of food Freezing of water Burning of a candle.​

User Merline
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Answer:

The chemical changes are: Growth of plant, Rusting of iron, cooking of food, Food digestion, Freezing of water, Burning of a candle

Step-by-step explanation:

growth of plant is a chemical change because it involves photosynthesis reaction , and many others reactions too.

Rusting of iron is a chemical change because a new substance iron oxide is formed. The presence of oxygen and water or water vapour is essential for rusting. Rusting of iron is a continuous process which slowly eats up the iron objects and makes them useless.

there is no any chemical change involved in mixing of iron filings and sand. iron fillings can be separated from sand by using magnetic separation.

Cooking of food is a chemical change as it involves the change in the composition of the food. After cooking, the raw ingredients of the vegetables cannot be regained.

Food digestion is considered a chemical change because enzymes in the stomach and intestines break down large macromolecules into simpler molecules so that the body can more easily absorb the food. In physical digestion, your body mechanically breaks down food, grinding or smashing it into smaller pieces.

Freezing is a physical change. It involves a liquid changing states to a solid. Thus, freezing a substance will not change its chemical identity, but its state.

The phenomenon which burning of candle belongs to both physical and chemical change. When a candle burns, the oxygen in the air reacts and forms carbon dioxide. A new substance, the CO2 is formed. So it is a chemical change.

User Bertvh
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