Pure substance, Mixture and Compounds Class-7th Goyal Brothers Chemistry Solutions Ch-3 Unit-2

Pure substance, Mixture and Compounds Class-7th Goyal Brothers Chemistry Solutions Ch-3 Unit-2. We Provide Step by Step Answers of Objective, True False , Fill in the blanks, Match the following , Study Questions of Chapter-3(Elements, compounds and mixture),Unit-2 (Pure substance, Mixture and compounds). Visit official Website  CISCE  for detail information about ICSE Board Class-7.

Pure substance, Mixture and Compounds Class-7th Goyal Brothers

Chemistry Solutions Chapter-3 Unit-2

Board ICSE
Class 7th
Subject Chemistry
Book Name Goyal Brothers
Theme-3 Elements, Compounds and Mixture
Unit-2 Pure substance, Mixture and compounds
Topic Solution of exercise questions
Session 2023-24

OBJECTIVE TYPE QUESTIONS

Chemistry Solutions Chapter-3 Unit-2

A. Fill in the blanks :

  1. Hydrogen and oxygen exist in water in the ratio 1:8 by _weight_.
  2. Ferrous sulphide is _black_ in colour.
  3. Brass is an alloy of the metals _copper_ and zinc.
  4. Compounds are _homogeneous_ in nature.
  5. Turmeric powder is _yellow_ in colour.

B. Statement given below are incorrect. write the correct correct statement:

1. Distilled water is a mixture.

Correct Statement: Distilled water is not a mixture.

2. Clear tap water is a pure substance.

Correct Statement: Clear tap water is not a pure substance.

3. Separation of Constituents of compound is possible through physical means.

Correct Statement: Separation of Constituents of compound is not possible through physical means.

4. Salt solution is an example of a heterogeneous mixture.

Correct Statement: Salt solution is an example of a homogeneous mixture.

5. The constituents of compound ferrous sulphide can be separated by using magnet.

Correct Statement: The constituents of compound ferrous sulphide can not be separated by using magnet.

C. Match the statement in Column A with those in Column B:

Column A

Column B

1. Iron and sulphur do not retain their properties in iron sulphide.

(a) Homogeneous

2. Brass and bronze are two metal-metal mixtures with a special name.

(b) Nitrogen

3. The solvent in a sugar solution.

(c) Alloy

4. A mixture whose constituents are mixed uniformly.

(d) Compound

5. Major component of air.

(e) Water

Answer:

Column A

Column B

1. Iron and sulphur do not retain their properties in iron sulphide.

(d) Compound

2. Brass and bronze are two metal-metal mixtures with a special name.

(c) Alloy

3. The solvent in a sugar solution.

(e) Water

4. A mixture whose constituents are mixed uniformly.

(a) Homogeneous

5. Major component of air.

(b) Nitrogen

D. Write ‘True’ or ‘False’ for the following statements :

  1. Muddy water is an example of homogeneous mixture. [F]
  2. Sugar solution is an example of homogeneous mixture. [T]
  3. Compounds retain the properties of its constituents. [F]
  4. Iron sulphide would get attracted to a nearby magnet. [F]
  5. Constituents of a mixture can be present in any desired ratio. [T]

E. Tick (√) the most appropriate answer.

1. Human blood is a :

(a) homogeneous solution

(b) heterogeneous solution

(c) mixture

(d) none of these

Ans: (b) heterogeneous solution

2. Energy exchanges do take place in :

(a) Formation of mixture

(b) Formation of solution

(c) Formation of compound

(d) none of these

Ans: (a) Formation of mixture

3. The colour of sulphur is :

(a) black

(b) grey

(c) yellow

(d) green

Ans: (c) yellow

4. Sulphur and iron react on heating to form :

(a) Phosgene

(b) iron sulphide

(c) molten iron

(d) molten sulphur

Ans: (b) iron sulphide

5. Which of the following is not a component of bronze?

(a) Aluminum

(b) copper

(c) zinc

(d) Tin

Ans: (a) Aluminum

STUDY QUESTIONS

Chemistry Solutions Chapter-3 Unit-2

Question 1. 

Categories the following as: mixture or compound

(a) Distilled water = Compound

(b)Ginger and garlic paste = Mixture

(c)Petrol = Mixture

(d)Wax = Compound

(e) Common salt = Compound

(f) Tincture of iodine = Mixture

Question 2. Name:

(a) Four compound from daily life

Answer: Four compound from daily life are Detergent, Toothpaste, Salt and Vineger.

(b) Four mixtures from daily life

Answer: Four mixtures from daily life are Soft-drinks, Cooking Gas, Cup of Coffee and Petrol.

(c) Three gaseous elements

Answer: Three gaseous elements are :-

  • Hydrogen as hydrogen gas (H2)
  • Oxygen as oxygen gas (O2)
  • Fluorine as fluorine gas (F2)

Question 3. Define :

(a) Heterogeneous mixture

Answer: A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. Example- Vegetable soup is a heterogeneous mixture.

(b)Homogeneous mixture

Answer: A homogeneous mixture is a gaseous, liquid or solid mixture that has the same proportions of its components throughout a given sample. It is uniform in composition throughout. There is only one phase of matter observed in a homogeneous mixture.

Question 4. Describe an experiment using which it can be proved that compounds do not retain properties of their constituents.

Answer: Take a small amount of mixture of iron and sulphur and roll a bar magnet in it. It is noticed that grey particles of iron cling to the magnet and yellow particles of sulphur left behind.

Now roll the magnet in the powdered iron sulphide compound. It is noticed that no iron particles cling to the magnet.

Thus, we can conclude that, constituents of a mixture can be separated by physical means, but the constituents of a compound cannot be separated by physical means

Question 5. Give two reasons to support that air is a mixture.

Answer: Air is a mixture because :-

(1) more than two gaseous components are mixed in an indefinite proportion.

(2) the components are not mixed chemically but interact with intermolecular forces.

(3) it does not have any specific chemical properties as each component differs chemically.

Question 6. Support with example that compound formation take place with energy changes, using water formation and iron sulphide formation.

Answer: The chemical reaction for water formation to show energy exchange we use the formula:

The burning of methane gas in plain air or in presence of oxygen we get:

As methane burns in air it forms carbon dioxide and water

The chemical reaction for sulphide formation to show energy exchange we use the formula:

Sulphide is usually attached with sodium or Hydrogen the formation or the chemical reaction for the sulphide is

The formation of sodium sulphide is formed by sodium hydrosulphur and sodium hydroxide. Boiling off the sodium sulphide we get the conjugate sulphide

Question 7. Give examples of any two mixtures and describe how the components can be separated.

Answer: The example are sugar in water ,ice ,air ,rock ,wood etc. yes they are mixtures.

Explanation: We can separate mixtures by physical methods like distillation, filteration etc.

— : end of Pure substance, Mixture and Compounds Class-7th Goyal Brothers Chemistry Solutions Ch-3 Unit-2 :–-

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