Which of the following are chemical chan | Class 9 Science Chapter Is Matter Around Us Pure, Is Matter Around Us Pure NCERT Solutions

Question:

Which of the following are chemical changes?

(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron filings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle.

Answer:

(a). Growth of a plant is a chemical change because at the time of photosynthesis, plants convert sunlight into chemical energy and this is an irreversible process.

(b). Rusting of iron is a chemical change because there is formation of new substance i.e.- Fe2O3, xH2O (Rust).

(c). Mixing of iron filings and sand is a physical change process.

(d). Cooking of food in a chemical change because there is change in chemical composition by supplying heat in addition to some food additives, oil, butter etc.

(e). Digestion of food is à chemical change because the enzyme present in stomach are break large macromolecules into simple molecules.

(f). Freezing of water is a physical change. because there is change in physical state of water notinitis composition.

(g). Burning of a candle is a chemical change because there is emission of CO2 and water vapours during the burning of candles.


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Is Matter Around Us Pure.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

Comments

Comment(s) on this Question

Welcome to the NCERT Solutions for Class 9 Science - Chapter . This page offers a step-by-step solution to the specific question from Excercise 5 , Question 11: Which of the following are chemical changes? (a) Growth of a plant (b) Rusting of iron (c) Mixi....