{"id":2317,"date":"2022-11-13T05:46:59","date_gmt":"2022-11-13T05:46:59","guid":{"rendered":"https:\/\/theexampillar.com\/ncert\/?p=2317"},"modified":"2022-11-29T06:42:05","modified_gmt":"2022-11-29T06:42:05","slug":"ncert-solutions-class-7-science-chapter-6-physical-and-chemical-changes","status":"publish","type":"post","link":"https:\/\/theexampillar.com\/ncert\/ncert-solutions-class-7-science-chapter-6-physical-and-chemical-changes\/","title":{"rendered":"NCERT Solutions Class 7 Science Chapter 6 Physical and Chemical Changes"},"content":{"rendered":"

NCERT Solutions Class 7 Science\u00a0<\/span><\/h2>\n

The NCERT Solutions in English Language for Class 7 Science Chapter – 6 (Physical and Chemical Changes) <\/strong>has been provided here to help the students in solving the questions from this exercise.<\/span><\/p>\n

Chapter – 6 (Physical and Chemical Changes)<\/span><\/h2>\n

1. Classify the changes involved in the following processes as physical or chemical changes:
\n<\/strong>(a) Photosynthesis
\n(b) Dissolving sugar in water
\n(c) Burning of coal
\n(d) Melting of wax
\n(e) Beating aluminium to make aluminium foil
\n(f ) Digestion of food<\/span><\/p>\n

Answer – <\/strong><\/span><\/p>\n

(a) Photosynthesis – Chemical change<\/strong>
\n(b) Dissolving sugar in water – Physical Change<\/strong>
\n(c) Burning of coal – Chemical change<\/strong>
\n(d) Melting of wax – Physical Change<\/strong>
\n(e) Beating aluminium to make aluminium foil – Physical Change<\/strong>
\n(f ) Digestion of food – Chemical change<\/strong><\/span><\/p>\n

2. State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
\n<\/strong>(a) Cutting a log of wood into pieces is a chemical change. (True\/False)
\n(b) Formation of manure from leaves is a physical change. (True\/False)
\n(c) Iron pipes coated with zinc do not get rusted easily. (True\/False)
\n(d) Iron and rust are the same substances. (True\/False)
\n(e) Condensation of steam is not a chemical change. (True\/False)<\/span><\/p>\n

Answer –
\n<\/strong>(a) Cutting a log of wood into pieces is a chemical change. (False)<\/strong>
\n(b) Formation of manure from leaves is a physical change. (False)<\/strong>
\n(c) Iron pipes coated with zinc do not get rusted easily. (True)<\/strong>
\n(d) Iron and rust are the same substances. (False)<\/strong>
\n(e) Condensation of steam is not a chemical change. (True)<\/strong><\/span><\/p>\n

3. Fill in the blanks in the following statements:
\n<\/strong>(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
\n(b) The chemical name of baking soda is _________.
\n(c) Two methods by which rusting of iron can be prevented are _________ and _________.
\n(d) Changes in which only _________ properties of a substance change are called physical changes.
\n(e) Changes in which new substances are formed are called _________ changes.<\/span><\/p>\n

Answer –
\n<\/strong>(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of\u00a0Calcium carbonate<\/span><\/strong>.
\n(b) The chemical name of baking soda is\u00a0Sodium hydrogen carbonate<\/span>.
\n<\/strong>(c) Two methods by which rusting of iron can be prevented are\u00a0painting<\/strong><\/span>\u00a0and\u00a0galvanization<\/strong><\/span>.
\n(d) Changes in which only\u00a0physical<\/strong><\/span>\u00a0properties of a substance change are called physical changes.
\n(e) Changes in which new substances are formed are called\u00a0chemical<\/strong><\/span>\u00a0changes.<\/span><\/p>\n

4. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.<\/strong><\/span><\/p>\n

Answer –\u00a0 <\/strong>When baking soda (Sodium hydrogen carbonate) is mixed with lemon juice (citric acid), bubbles are formed. The bubbles are formed due to the evolution of carbon dioxide gas. This is a chemical change. In this change, citric acid contained in lemon juice reacts with sodium hydrogen carbonate which results in the evolution of carbon dioxide gas.
\nLemon juice + Baking soda \u2192 Carbon dioxide + other substances Citric acid Sodium Hydrogen carbonate<\/span><\/p>\n

5. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.<\/strong><\/span><\/p>\n

Answer –
\n<\/strong>Candle Burning
\n<\/strong>Physical change\u00a0\u2192<\/span><\/span><\/span><\/span><\/span>\u00a0Melting of wax
\nChemical change\u00a0\u2192<\/span><\/span><\/span><\/span><\/span> Burning of wax<\/span><\/p>\n

Digestion of Food
\n<\/strong>Physical change\u00a0\u2192<\/span><\/span><\/span><\/span><\/span>\u00a0Breaking down of larger food particles into smaller particles
\nChemical change \u2192<\/span><\/span><\/span><\/span><\/span>\u00a0Digestion of food<\/span><\/p>\n

6. How would you show that setting of curd is a chemical change?<\/strong><\/span><\/p>\n

Answer –\u00a0 <\/strong>Once the curd is formed, milk cannot be re-obtained from it. Also, both milk and curd have different properties. Since these are the properties of a chemical change, setting of curd is a chemical change.<\/span><\/p>\n

7. Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.<\/strong><\/span><\/p>\n

Answer –\u00a0 <\/strong>When we burn wood, a new substance, coal, is formed. Therefore, it is a chemical change. However, when we cut wood, only the shape and size of the wood are changed. No new substance is formed. Therefore, it is a physical change.<\/span><\/p>\n

8. Describe how crystals of copper sulphate are prepared.<\/strong><\/span><\/p>\n

Answer –\u00a0 <\/strong>Crystals of copper sulphate are prepared by the method of\u00a0crystallisation\u00a0<\/strong>.\u00a0<\/span><\/p>\n

The process is as follows:<\/span><\/p>\n