GIVE REASONS FOR THE FOLLOWING-
A- BURNING OF A CANDLE INVOLVES BOTH PHYSICAL AND CHEMICAL CHANGE .
B-WHY IS DIGESTION IS PHYSICAL AND CHEMICAL CHANGE .
C-RUSTING OF AN IRON IS MORE PREVELANT IN COASTAL AREAS AS COMPARED TO DESART AREA.
WHY IS CURDING OF MILK IS CHEMICAL CHANGE.
PLEASE ANSWER MY QUESTION IN EASY WORDS
Answers
Answer:
Ans(a) When a candle burns, both physical & chemical changes occur. On heating, candle wax melts and form liquid wax. It is a physical change. ... When a candle is burnt in air, the mass of the product is increased due to atmospheric oxygen which show a that it is a chemical change.
Ans(b) Digestion is considered a physical and 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. ... So, water freezing to ice or boiling to steam is a physical change, not a chemical one.
Ans(c) In coastal areas the quantity of moisture present in air is higher than in the deserts. Hence, rusting of iron objects is faster in coastal areas than in deserts.
Milk contains casein protein and this protein reacts with the lactic acid. Lactic acid breaks the chemical structures/bonds of the milk and forms new bonds thus giving rise to a semi-solid form of milk called curd. ... Hence, curdling milk is a chemical change.