Class IX - Science Practice Paper - 5 - Answers

Subject: Science

Class IX

Time Allowed: 3 hours

Max Marks: 80

General Instructions:

The question paper comprises four sections A, B, C and D. there are 37 questions in the question paper. All questions are compulsory.
Section A question no 1 – 20 – all questions and parts thereof are of one mark each.
Section B question no 21 – 26 are short answer type questions carrying 2 marks each.
Section C question no 27 – 34 are short answer type questions, carrying 3 marks each.
Section D question no 35 – 37 are long answer type questions carrying 5 marks each
There is no overall choice. However, internal choices have been provided in some questions.
Wherever necessary, neat and properly labelled diagrams should be drawn.

Section – A

1. What is the kinetic energy of an object?

View Answer

Ans. Kinetic energy is the energy due to motion of the object.

If the speed of the body is halved, what is the change in its kinetic energy?

View Answer

Ans. As K.E = ½ mv², if the speed of the body is halved its kinetic energy is reduced to ¼ of its original value.

2. While getting down a moving bus, why should a person run in the same direction as that of the bus?

View Answer

Ans. A person in a moving bus possesses inertia of motion. Thus, if he simply jumps out, his feet suddenly comes to rest, but his body continues moving in the direction of bus. Thus, he can fall forward and may cause serious injury to himself. However, if the person starts running in the direction of the bus, his body will not come to rest and he will not fall in the forward direction.

2. A change in the physical state can be brought about

A) only when energy is given to the system

B) only when energy is taken out from the system

C) when energy is either given to, or taken out from the system.

D) without any energy change

View Answer

Ans (C)

4. What is the undefined nuclear region of prokaryotes called?

View Answer

Ans. the undefined nuclear region of a prokaryotic cell is called nucleoid.

5. Name (i) the cells which have changing shape, (ii) the cells which have a typical shape.

View Answer

Ans. (i) Amoeba (ii) Nerve cell

6. State the role of large air cavities present in parenchyma of aquatic plants.

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Ans. Storage of metabolic gases (CO₂, O₂) and providing buoyancy.

Which tissue has dead cells?

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Ans. Sclerenchyma tissue is composed of dead cells

7. Where are proteins synthesized inside the cell?

View Answer

Ans. Ribosomes.

8. How can the velocity of an object be changed?

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Ans. It can be changed by changing either:

(i) the object’s speed

(ii) direction of motion, or

(iii) both

9. 10 gm of silver nitrate solution is added to 10 gm of sodium chloride. What change in mass do you expect after the reaction and why?

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Ans. No change in mass will take place because law of conservation of mass holds good.

What is Gram atomic mass?

View Answer

Ans. It is the atomic mass of an element expressed in terms of grams.

10. Which of the following are chemical changes?

(i) Decaying of wood

(ii) Burning of wood

(iii) Sawing of wood

(iv) Hammering of a nail into a piece of wood

A) (i) and (ii)

B) (ii) and (iii)

C) (iii) and (iv)

D) (i) and (iv)

View Answer

Ans. (A)

Reason: Decaying of wood and burning of wood are chemical changes, because in these processes, the chemical composition of wood is changed and new substances are formed, which cannot be converted back into their original form. Sawing of wood and hammering of a nail into piece of wood are physical changes.

11. Which postulates of Dalton’s atomic theory can explain the law of definite proportions?

View Answer

Ans. The Law of Definite Proportions is explained by the following postulate of Dalton: “ The relative number and kinds of atoms are constant in a given compound.”

12. A runner presses the ground with his feet before he starts his run. Identify action and reaction in this situation.

View Answer

Ans. Person presses his foot against the ground – Action

Ground exerts an equal and opposite force – Reaction

Find the acceleration produced by a force of 12 N exerted on an object of mass 3 kg.

View Answer

Ans. F = ma

12 = 3 x a
a = 12/3 = 4 m/s²

13. What is a heterogeneous mixture?

View Answer

Ans. A mixture that does not have uniform composition throughout its mass is called a heterogeneous mixture.

14. Give any two example of the crops grown in two-year rotation.

View Answer

Ans. Maize, potato, sugarcane, peas

For question number 15, 16 and 17, two statements are given – one labelled Assertion (A) and the other Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

A) Both A and R are true, and R is correct explanation of the assertion

B) Both A and R are true, and R is not the correct explanation of the assertion

C) A is true, but R is false

D) A is false, but R is true

15. Assertion: Relative atomic mass of the atom of element is the average masses of the atom as compared to 1/12^th the mass of one carbon-12 atom.

Reason: Carbon-12 isotope is the standard reference for measuring atomic masses.

A) Both A and R are true, and R is correct explanation of the assertion

B) Both A and R are true, and R is not the correct explanation 6of the assertion

C) A is true, but R is false

D) A is false, but R is true

View Answer

Ans. (B)

Assertion: Valency of helium is zero.

Reason: Atomic number (Z) of helium is 2. Its electronic configuration is K(2). This means that its atom has completely filled shell which is the only shell it has.

A) Both A and R are true, and R is correct explanation of the assertion

B) Both A and R are true, and R is not the correct explanation of the assertion

C) A is true, but R is false

D) A is false, but R is true

View Answer

Ans. (A)

16. Assertion: If a spring is stretched from one side, the size and shape of the spring changes.

Reason: Unbalanced force acting on the spring changes the size and shape of the spring in the direction of application.

A) Both A and R are true, and R is correct explanation of the assertion

B) Both A and R are true, and R is not the correct explanation of the assertion

C) A is true, but R is false

D) A is false, but R is true

View Answer

Ans. (A)

17. Assertion: Mitochondria are semi-autonomous cell organelle

Reason: Mitochondria generate energy

A) Both A and R are true, and R is correct explanation of the assertion

B) Both A and R are true, and R is not the correct explanation of the assertion

C) A is true, but R is false

D) A is false, but R is true

View Answer

Ans. (B)

Q. No 18 -20 contain five sub-parts each. You are expected to answer any four sub parts in these questions:

18. Read the following and answer any four questions from 18 (i) to 18 (v)

75 kg missile is dropped downwards from an air plane, and has a speed of 60 m/s at an altitude of 850 m above the ground. Determine:

(i) The K.E. possessed by the missile at 850 m

View Answer

Ans. Given: Mass of the missile, m = 75 kg and Speed v = 60 m/s

Therefore K.E. = ½ mv²

= ½ x 75 x 60 x 60

= 13500 J

(ii) The P.E possessed by the missile at 850 m

View Answer

Ans. Given, Mass of the missile, m = 75 kg, Acceleration due to gravity g = 10 m/s²Height h = 850 m

Therefore, PE = m x g x h

= 75 x 10 x 850

= 637500 J

(iii) The total mechanical energy possessed by the missile

View Answer

Ans. Total mechanical energy of the missile = K.E + P.E

= 13500 + 637500

= 7.7 x 10⁵ J

(iv) The K.E. and velocity with which it strikes the ground

View Answer

Ans. K.E at the ground = 7.7 x 10⁵ J

K.E = ½ mv²

Therefore, v² = 2 K.E/m

On putting the value, velocity with which missile strikes the ground = 143.2 m/s

(v) The energy possessed by an object due to motion is ________

A) chemical energy

B) kinetic energy

C) potential energy

D) power

View Answer

Ans. (B)

19. Read the following and answer any four questions from 19 (i) to 19 (v)

Leucoplasts are colourless plastids. They store starch, oil, proteins. Chromoplasts are coloured plastids. They contain pigments, e.g. Chloroplasts contain green pigment present in plant cell. Chromoplasts provide colour to various flowers and fruits.

(i) What is the function of leucoplasts?

View Answer

Ans. Leucoplasts store starch, oil, proteins.

(ii) Which plastids provide colour to fruits and flowers?

A) Leucoplasts

B) Chromoplasts

C) Chloroplasts

D) Proteinoplast

View Answer

Ans. (B)

(iii) Which of the following statement is true?

A) Plastids are present in both plant and animal cell

B) Plastids are absent in plant as well as animal cell

C) Plastids are present only in plant cell

D) Plastids are present only in animal cell

View Answer

Ans. (C)

(iv) Name the plastids, which contain green pigment?

View Answer

Ans. Chloroplasts is the chief plastid present in plant cells containing the green pigment called chlorophyll.

v) Name the plastids, which brings about the process of photosynthesis?

View Answer

Ans. Chlorophyll acts as the site of photosynthesis and it is present only in the plant cells.

20. Read the following and answer any 4 questions from 20 (i) and 20 (v)

Amit buys few grams of gold at the poles as per the instruction of one of his friends. He lands over the same when he meets him at the equator.

i) At what place on the earth’s surface is the weight of a body minimum?

A) At the equator

B) At all place the weight will be equal

C) At the north pole

D) At the south pole

View Answer

Ans. (A)

ii) Which of the following statement is true?

A) The friend at equator will agree with the weight of gold bought at poles

B) The friend at equator will not agree with the weight of gold bought at poles

C) The friends at the poles will not agree with the weight of gold bought at poles

D) The friends at equator as well as at the poles will agree with the weight of gold bought at poles.

View Answer

Ans. (B)

iii) The value of g is greater at the poles than at the equator, so the weight of gold at the equator will be

A) more than the weight of gold at the poles

B) less than the weight of gold at the poles

C) same as the weight of gold at the poles

D) zero

View Answer

Ans. (B)

iv) What is the relation between mass and weight?

A) Weight (W) of the body is always less than the mass of the body

B) Weight (W) of the body is same as that of the mass of the body

C) Weight (W) of the body is inversely proportional to the mass of the body.

D) Weight (W) of the body is directly proportional to the mass of the body.

View Answer

Ans. (D)

v) What is the SI unit of Mass?

View Answer

Ans. The SI unit of mass is kilogram.

Section – B

21. How are the following related to each other?

(i) Chromotin network and chromosomes

View Answer

Ans. On cell division, chromatin network organise themselves into chromosomes.

(ii) Chloroplast and chlorophyll

View Answer

Ans. Chloroplast is a plastid which contains a green pigment called chlorophyll which is responsible for photosynthesis.

Draw a diagram of a plant cell and label it’s any four parts.

View Answer

Ans.

22. Give two reasons as to why there is tremendous scope to develop fisheries in India.

View Answer

Ans. There is good scope for fisheries in India because:

(i) India has 1.6 million hectares of inland water bodies.

(ii) Its coastline is 7500 km long.

23. Can a homogeneous mixture have a variable composition? Justify giving an example.

View Answer

Ans. Yes, homogeneous mixtures can have a variable composition. For example

(i) Fe + H₂SO₄ (aq) — > FeSO₄ + H₂

(ii) FeS + H₂SO₄ (aq) — > FeSO₄ + H₂S

Mention any two differences between physical and chemical changes.

View Answer

Ans. Physical change: Reversible change, chemical composition does not change, no new substance is formed.

Chemical change: Irreversible change, chemical composition changes, new substances is formed

Example: Tearing a paper – physical change

Burning a match stick – chemical change

24. List any two properties for each of the following case of metals which make them suitable to be used as:

(i) Utensils for cooking food

View Answer

Ans. Metals are malleable and good conductors of heat.

(ii) Wires for electrical connections

View Answer

Ans. Metals are ductile and good conductors of electricity

25. If you divide the total distance travelled on a car trip by the time for the trip, are you calculating the average speed or the magnitude of the average velocity? Under what circumstances are these two quantities the same?

View Answer

Ans. If we divide the total distance travelled on a car trip by the time for the trip, we are calculating the average speed.

The average speed and the average velocity are same when the object travels in a straight line and in one direction

Since, average speed = Total distance travelled/Total time taken

Average velocity = Net Displacement/Total time taken

The magnitudes of both will be equal when the total distance travelled is equal to displacement. This happens when an object moves in a straight line and in unidirectional motion.

26. A body of mass 15 kg possesses kinetic energy of 18.75 kJ. Find the velocity.

View Answer

Ans. K.E = ½ mv² = 18.75 kJ = 18750 J

v² = (18750 x 2)/15 = 50 m/s

Section – C

27. Explain the following type of motion with one example for each.

(i) acceleration is positive

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Ans. Here, the motion is accelerated motion, e.g. car moving on a road with increasing velocity

(ii) acceleration is negative

View Answer

Ans. Here, the motion is retarded motion e.g. Brakes applied to a moving car

(iii) acceleration is zero

View Answer

Ans. Here, the motion is uniform motion e.g. Car moving with a constant speed along a road.

A particle moves over three quarters of a circle of radius r cm. Calculate the magnitude of its distance and displacement.

View Answer

Ans.

A particle moves over three quarters of a circle of radius r cm

Distance travelled = 2πr x ¾ = 2/3πr cm

Displacement = AD

AD = √ (r2 + r2) = r√2 cm

28. Write the name of different plant parts in which chromoplast, chloroplast and leucoplast are present.

View Answer

Ans. (i) Chromoplasts are plastids, which are involved in different coloured pigment synthesis and their storage. It is responsible for giving different colours to the flowers, fruits.

(ii) The chloroplast is involved in carrying out photosynthesis. It gives a green colour to leaves.

(iii) Leucoplasts are involved in storage functions. Such, colourless plastid is present in underground roots, stems.

Draw a diagram of cardiac muscle and label any two parts. Write one main function of cardiac muscle.

View Answer

Ans.

Cardiac muscles

Function: Beating of heart

29. Write one function each of – Ribosomes, Vacuole, Plasma membrane

View Answer

Ans. (i) Ribosomes: It helps in protein synthesis

(ii) Vacuole: Vacuoles are full of cell sap and provide turgidity and rigidity to the cell in plants.

(iii) Plasma membrane: It allows or permits the entry and exit of some materials in and out of the cell. It prevents movement of some other materials not required or are harmful for cells.

30. Tabulate two differences between balanced and unbalanced forces. Write one example of each.

View Answer

Ans.

S. No	Balanced force	Unbalanced force
(i)	The net effect produced by a number of forces on a body is zero.	The net effect produced by a number of forces on a body is non-zero.
(ii)	It can only bring a change in the shape of the body.	It causes a change in state of rest or of uniform motion of abody.
(iii)	Example: Tug of war	Example: Moving an object

31. In a reaction 4.6 gm of barium chloride reacted with 3.4 gm of sodium sulphate. The products were 2.8 gm of sodium chloride and 5.2 gm of barium sulphate. The reaction takes place as follows:

Barium chloride + Sodium sulphate — > Sodium chloride + Barium sulphate

Show that the above observation is in agreement with law of conservation of mass. State the law.

View Answer

Ans. 4.6 g + 3.4 g — > 2.8 g + 5.2 g

8 g — > 8 g

This is in agreement with the ‘Law of Conservation of Mass’ that states that matter can neither be created nor destroyed in a chemical reaction.

32. What is meant by acceleration due to gravity? Derive an expression for acceleration due to gravity in terms of mass M of earth and its radius R

View Answer

Ans. The acceleration produced in the motion of a body falling freely under the force of gravity is called acceleration due to gravity. It is denoted by ‘g’

Consider the earth to be a sphere of mass M and radius R. Suppose a body of mass m situated at distance r from the centre of the earth.

As we know, according to Newton’s law of gravitation, the force of attraction between the earth and the body is given by

F = GmM/r² —– (i)

This force produces an acceleration ‘g’ called acceleration due to gravity in the body of mass m.

So, from Newton’s second law

F = mg —– (ii)

From equations (i) and (ii) , we get

Mg = GMm/r²

Or g = GM/r²

This equation gives acceleration due to gravity at the surface of the earth.

The value of ‘g’ on the earth’s surface is 9.8 ms^-2

33. List any two differences between electrons, protons and neutron.

View Answer

Ans.

34. State the meaning of Layers. Why limestone is added in their diet? Name one other dietary requirement of of poultry birds

View Answer

Ans. Layers are the birds, reared for egg production.

Limestone is added in their diet to form the shell of eggs.

Other example: Proteins and roughage.

Section – D

35. Calculate the electricity bill amount for a month of 30 days, if the following devices are used as specified:

(i) 2 bulbs of 40 W for 6 hours

View Answer

Ans. 2 bulbs of 40 watts for 6 hrs

E_1bulb = 2 x 40 x 6 = 480 W = 0.48 kWh

(ii) 2 tube lights of 50 W for 8 hours

View Answer

Ans. E_2tubelight = 50 x 8 x 2 = 0.800 kWh

(iii) A TV of 120 W for 6 hours

Given that cost of electricity is Rs 2.50 per unit

View Answer

Ans. E_TV = 120 x 6 = 0.729kWh

Total energy = 0.48 + 0.80 + 0.72 = 2.00 units

Rate = Rs 2.50 per unit

Cost per day = 2 x 2.50 = Rs 5.00

Cost of 30 days = 5.00 x 30 = Rs 150

(i) Justify that “a body at a greater height has larger energy”

View Answer

Ans. At a particular height total energy

P.E = mgh

i.e., Energy ∝ height

So more is the height more is the energy

(ii) A body of mass 2kg is thrown up at a velocity of 10 m/s. Find the potential energy at the highest point.

View Answer

Ans. m = 2 kg, u = 10 m/s, v = 0, a = -g

From v² = u² + 2gh

u²= 2gh
h = u2/2g = (10 x 10)/(2 x 10) = 5 m
P.E = mgh
= 2 x 10 x 5
100 J

36 (a) Give three medical uses of ultrasound.

View Answer

Ans. Three medical uses of ultrasound are:

(i) Electrocardiography

(ii) Ultrasonography

(iii) To break small stones formed in the kidneys into the grains

(b) A ship which is stationary is at a distance of 2800 m from the sea-bed. The ship sends an ultrasound signal to the sea-bed and its echo is heard after 4 s. Find the speed of sound in water.

View Answer

Ans. Distance = 2800 m

Time = 4 second

Velocity =?

2d = v x t

2d/t = v

v = 2 x 2800/4

= 1400 m/s

37. Complete the following flowchart:

View Answer

Ans. (a) Connective

(b) Plasma

(d) Platelets

(e) Neutrophil

(f) Eosinophil

(g) Lymphocyte

(i) Monocyte

(j) Bone or ligament or tendon

Class IX – Science Practice Paper – 5 – Answers