## Samacheer Kalvi 9th Term I Science Book Back Question and Answers – Unit 4:

Samacheer Kalvi 9th Standard New Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 9 New Syllabus 2021 to 2022 Book Back Ques & Ans solutions available for both English and Tamil Medium. Class 9 Science Book Term 1 Unit 4 – Matter Around Us Answers/Solutions are provided on this page. 9th Std Science Book is of Term 1st, 2nd, 3rd, and consists of 9 Units in each Term. All 9 Units of Term 1st, 2nd, 3rd Science Book Back One, and Two Mark Solutions are given below.

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### Samacheer Kalvi 9th Science Book Back Unit 4 Term 1 Solutions Guide PDF:

Science Subject 1 Mark and 2 Mark Solutions Guide PDF available below. Click the Download option to download the book back 1 Mark & 2 Mark questions and answers. Take the printout and use it for exam purposes.

### Unit – 4

Matter Around Us

1. The physical state of water at 373k is …………….
a) solid
b) liquid
c) vapour
d) plasma

2. Aniont the following ………is a mixture
a) common salt
b) juice
c) carbon dioxide
d) pure silver

3. When we mix a drop of ink in water we get a …………….
a) Heterogeneous Mixture
b) Homogeneous Mixture
c) Compound
d) Suspension

4. The constituents that form a mixture are also called ………………
a) Elements
b) compounds
c) alloys
d) components

5. …………….has the same properties throughout the sample.
a) pure substance
b) mixture
c) colloid
d) suspension

II. State whether the following statements are True or False. If false give the correct statement.

1. Liquids expand more than gases on heating.
Ans: False – Gases expand considerably on heating.

2. A compound cannot be broken into simpler substances chemically.
Ans: False – can be spitted into new substances by chemical methods.

3. Water has a definite boiling point and freezing point.
Ans: True

4. Buttermilk is an example of heterogeneous mixture.
Ans: True

5. Aspirin is composed of 60% Carbon, 4.5% Hydrogen and 35.5% Oxygen by mass. Aspirin is a mixture.
Ans: False, Aspirin is a compound.

III. Match the following:

A                                               B
i) Element         – a) Settles down on standing.
ii) Compound   – b) Impure substance
iii) Colloid         – c) Made up of molecules
iv) Suspension – d) Pure substance
v) Mixture         – e) Made up of atoms

Ans: (i) – e; (ii) – d; (iii) – c; (iv) –a; (v) – b

IV. Fill in the blanks:

1. Evaporation is always accompanied by decrease in temperature.
2. 150oC = 423K
3. A homogeneous mixture has no distinguishable boundary between its components.
4. An example of a substance that sublimes is naphthalene
5. Latent heat is the energy used for inter conversion of matter

1. Why is it possible to row a boat in water but not pass through a wooden fence.
Ans: There are gaps between the molecules of water.

2. How does gaseous pressure arise?
Ans: The rapid motion and collision of molecules with the walls of the container causes pressure.

3. Define sublimation?
Ans: The process of conversion of matter from solid state directly into vapour state (without going to liquid state).

4. Which state of matter has the highest kinetic energy?
Ans: Gaseous state of matter.

5. A few drops of ‘dettol’ when added to water the mixture turns turbid. Why?
Ans: The oil droplets of dettol get suspended in water and create an emulsion.

1. Why are gases easily compressible whereas solids are incompressible?
Ans: The atoms and molecules in gases are much more spread out than in solids or liquids. They move freely and vibrate freely at high speed.

2. Hold a ‘Smiley ball’ and squeeze it can you compress it? Justify your answer.
Ans: A smiley ball has minute holes, in which air is trapped. When we press it the air is expelled out. So we are able to compress.

3. Which of the following are pure substances?
Ice, Milk, Iron, Hydrochloric acid, Mercury, Brick and water,
Ans: Iron, Hydrochloric acid, Mercury and water.

4. Oxygen is very essential for us to live. If forms 21% of air by volume. Is it at element or compound?
Ans: it is an element.

5. You have just won a medal made of 24-carat gold. Have you just procured a pure substance or an impure substance?
Ans: A pure substance. Because it is an alloy.