CBSE Sample Papers for Class 9 Science Paper 7

CBSE Sample Papers for Class 9 Science Paper 7 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 7.

CBSE Sample Papers for Class 9 Science Paper 7

Board	CBSE
Class	IX
Subject	Science
Sample Paper Set	Paper 7
Category	CBSE Sample Papers

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 7 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. How ever an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
Define average speed.

Question 2.
Pick up the isotopes among the following and state reason.

Question 3.
What is formula unit mass? How is it different from molecular mass?

Question 4.
In your everyday life you come across a range of motions in which

1. acceleration is in the direction of motion,
2. acceleration is against the direction of motion,
3. acceleration is uniform,
4. acceleration is non-uniform.

Can you identify one example each of the above type of motion?

Question 5.
Na⁺ has completely filled K and L shells. Explain.

Question 6.
In a high jump athletic event, why are athletes made to fall either on a cushioned bed or on a sand bed?

Question 7.
Define valency, explain by taking examples of silicon and oxygen.

Question 8.
What are the immunisation programmes available at the nearest health centre in your locality? Which diseases may become the major health problems in your area?
OR
If someone in the family gets infectious disease, what precautions will you advice to the other family members?

Question 9.
Give the functions of nuclear membrane. What is endocytosis?
OR
What is the function of plastids?

Question 10.
A trolley, while going down an inclined plane, has an acceleration of 2 cm s^-2. What will be its velocity 3 seconds after the start?

Question 11.
Complete the following table:

Question 12.
What are the three atomic species of hydrogen?

Question 13.
An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?

Question 14.
What are fertilisers? Excess use of fertilisers is not advisable, explain.

Question 15.
Few villages in Punjab were upset as canals that brought water to their village were full of chemical and froth in it. They could not use this water for farming. The Panchayat found that it was a chemical factory nearby that dumped the waste in canal. After lot of hue and cry the company stopped dumping the waste in canals.

1. State two causes of water pollution.
2. Name any two harmful effects of polluted water.
3. State the values of both the factory people and Panchayat of the village, reflected in this act.

Question 16.
State Archimedes’ principle. What are fluids? Why is Archimedes’ principle applicable only for fluids? Give the application of Archimedes’ principle.

Question 17.
Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it involving violation of law of conservation of energy?

Question 18.
What are manures? Give its biological classification. How does insect pests attack the plant and affect its growth?

Question 19.
(a) A hockey ball of mass 200 g travelling at 10 ms 1 is struck with a hockey stick so as to return along its original path with a velocity of 5 ms ^-1. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.
(b) Abulletofmass 10 g travelling horizontally with a velocity of 150 ms^-1 strikes a stationary wooden block and comes to rest in 0.03 s. Calculate the distance of penetration of the bullet into the block. Also calculate the magnitude of the force exerted by the wooden block on the bullet.

Question 20.
Show that
(a) the acceleration due to gravity at the surface of moon is about one-sixth of that at the surface of the earth.
(b) the weight of the body on moon = 1/6 th the weight of the body on earth.
OR
What is inertia? Explain different types of inertia and give three daily life examples related to it.

Question 21.
Give two practical applications of reflection of sound waves. Explain how bats use ultrasound to catch a prey.

SECTION-B

Question 22.
A mixture of soil and water was shaken well and then tested for its appearance, stability and sedimentation. What should be the observation in this experiment?

Question 23.
While determining the density of the material of a sphere, using a spring balance and a measuring cylinder, a student noted the following readings

1. mass of the sphere = 81 g
2. reading of water level in the cylinder without the sphere in it = 54 mL
3. reading of water level in the cylinder with the sphere in it = 63 mL
   On the basis of these observations, calculate the density of the material of the sphere in Kg/m.

Question 24.
There are two tubes, A is wide and B is narrow, which one is suitable for making stethoscope?

Question 25.
What is cutaneous respiration?

Question 26.
What is the principle of working of a pressure cooker?

Question 27.
Name two functions that are common to roots and rhizoids?

Answers
SECTION-A

Answer 1.
The total distance travelled by an object divided by the total time taken.

Answer 2.
The isotopes are \(_{ 17 }^{ 35 }{ X }\) and \(_{ 17 }^{ 37 }{ X }\) as both the atoms have same atomic number but different mass number.

Answer 3.
The formula unit mass of a substance is the sum of the atomic masses of all the atoms present in the formula unit of a compound.
Formula unit mass is used for ionic compounds which have ions as their constituent particles. Molecular mass is used for molecules which have neutral atoms as their constituent particles.

Answer 4.

1. A car moving on a road.
2. A ball thrown up.
3. Fan blades rotating.
4. Wind mill at times moves faster when the wind speed is more and becomes slow as the wind speed decreases.

Answer 5.
Sodium atom (Na) has atomic number = 11
Number of protons = 11
Number of electrons = 11
Electronic configuration of Na = K L M
Sodium atom (Na) loses 1 electron to become stable and form Na+ ion. Hence it has completely filled K and L shells.

Answer 6.
In a high jump athletic event, athletes are made to fall either on a cushioned bed or on a sand bed so as to increase the time of the athlete’s fall to stop after making the jump.
This decreases the rate of change of momentum and hence the force. Due to decrease in the rate of change of momentum and force, there will be less reaction force acting on the body of athlete thus, there is very minimal or no change of injuiy.

Answer 7.
Valency is the combining capacity of the atom of an element.
Atomic number of oxygen = 8
Atomic number of silicon = 14
Electronic configuration of oxygen = 2 6 4
Electronic configuration of silicon = 2 8 4
In the atoms of oxygen there are 6 valence electrons (i.e., electrons in the outermost shell). To fill the orbit, 2 more electrons are required. In the atom of silicon, there are 4 valence electrons. To fill the orbit, 4 more electrons are required.
Hence, the combining capacity of oxygen is 2 and that of silicon is 4.
i. e., Valency of oxygen = 2
Valency of silicon = 4

Answer 8.
The immunisation programmes available at the nearest health care centres are:

• Child immunisation programme for the children of age group 0 to 12 months.
• Polio eradication programme
• H₁N₁ screening programme

Age	Immunisation
Infants	Polio, B.C.G
6 weeks-9 weeks	D.P.T, tetanus
9-12 months	booster doses, chickenpox, hepatitis A, B etc.

In many areas tuberculosis cases are reported in a large number, which is a major health concern.
OR
If any person suffering from any infectious disease in the family then following precautions should be taken:

• The surroundings and the house should be clean.
• The clothes and utensils of patient should be sterilised regularly.
• Separate towels and handkerchief should be used by the patient.
• Clean and boiled drinking water and balanced nutritious diet should be given to the patient.
• Silence should be maintained and the patient should be given a lot of bed rest to overcome the infection in a separate room.
• Children should not be allowed to visit the room of the infected person.

Answer 9.
The nuclear membrane present as an outer covering in the nucleus allows the transfer of materials inside and out of the nucleus to cytoplasm. It also helps in maintaining the shape of the nucleus.
The cell membranes flexibility allows the cell engulf in food and other material from its external environment. This process is known as endocytosis. E.g., Amoeba acquires its food through such processes.

OR
Plastids are the cell organelles present only in plant cells. There are two types of plastids chromoplasts (coloured plastids) and leucoplasts (white or colourless)
Chromoplast: These are the coloured plastids and consists of coloured pigments, which gives different colours to flowers, fruits and leaves. The green coloured pigment present in leaf is called chlorophyll which helps in the photosynthesis. It is present in the plastid called chioroplast.
Leucoplast: These are white or colourless plastids, which mainly stores starch, oil and protein granules in it.

Answer 10.
a = 2 cm/s², t = 3 s, v = ?, u = 0
v = u + at
= 0 + 2 × 3
v = 6 cm/s
∴ The velocity of a trolley 3 s after the start will be 6 cm/s.

Answer 11.

Atomic Number	Mass Number	Number of Neutrons	Number of Protons	Number of Electrons	Name of the Atomic Species
9	19	10	9	9	Fluorine
16	32	16	16	16	Sulphur
12	24	12	12	12	Magnesium
1	2	1	1	1	Deuterium
1	1	0	1	0	Hydrogen
17	35	18	17	17	Chlorine

Answer 12.
Three atomic species of hydrogen are:

Name	Protium \(_{ 1 }^{ 1 }{ H }\)	Deuterium \(_{ 1 }^{ 2 }{ H }\)	Tritium \(_{ 1 }^{ 3 }{ H }\)
Symbol	\(_{ 1 }^{ 1 }{ H }\)	\(_{ 1 }^{ 2 }{ H }\)	\(_{ 1 }^{ 3 }{ H }\)
Protons	1	1	1
Atomic number	1	1	1
Neutrons	0	1	2

Answer 13.
Diameter = 200 m, r = \(\frac { d }{ 2 }\) = 100 m
Time taken for one round = 40 s
Distance travelled in 2 minutes and 20 s = (2 × 60) + 20 = 140 s
\(\frac { 140 }{ 40 }\) = 3.5 rounds
Distance travelled = Circumference of the circle × 3.5
= 2πr × 3.5
= 2 × \(\frac { 22 }{ 7 }\) × 100 × 3.5 = 2200 m
Displacement after 3.5 revolutions
= Diameter of the track
= 200 m

Answer 14.
Fertilisers are obtained artificially on a commercial basis. It is a chemical subtance which contains the nutrients required for the crops to grow. Fertilisers supply various nutrients as they are nutrient specific, e.g. urea provides nitrogen. Mixed fertiliser provides any two or a mixture of nutrients.
They are expensive but their use yield large production but due to their costs, they are a major factor of high cost farming.
Excessive use of fertilisers are not advisable as:

• It leads to soil and water pollution.
• It can destroy the fertility of soil. As the soil is not replenished, microorganisms in the soil are harmed by fertilisers.

Answer 15.

1. Two causes of water pollution are sewage and effluent from the industries dumped in the water bodies.
2. Two harmful effects of water pollution are:
   • It may cause diseases like cholera, typhoid etc.
   • Many life-forms/water creatures may die due to the presence of pollutants in water.
3. Irresponsible behaviour of the factory people and moral responsibility of the village panchayat is reflected in this act.

Answer 16.
Archimedes’ principle – When a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it. It is used in designing of ships and submarines and for many other purposes.

Fluids are the substances which can flow e.g., gases and liquids are fluids.
Archimedes’ principle is based on the upward force exerted by fluids on any object immersed in the fluid. Hence it is applicable only for fluids.
Applications of Archimedes’ principle:

1. It is used in designing of ships and submarines.
2. It is used in designing of lactometer, which is used to determine the purity of milk.
3. To make hydrometer that is used to determine the density of a liquid.

Answer 17.
Let ‘A’ be the mean position of the pendulum. When it is raised to point ‘B’ and then released, it starts oscillating from B to A, A to C and back to A. It repeats this motion again and again.
At point B and C, height of pendulum is maximum, hence the potential energy at these points is maximum.

During the oscillation, when pendulum moves from B – A – C, its maximum speed is at A, hence the maximum kinetic energy is at A, and potential energy at this point is minimum.
This shows that potential energy at B is transformed into kinetic energy at A and again this energy is transformed into potential energy at C.

This transformation of energy goes on as the pendulum oscillates, it does not involve violation of law of conservation of energy.
Bob comes to rest because there are three forces acting on it,

1. Gravitational force exerted by earth ‘g’, which tries to bring the bob at rest.
2. Air resistance force that acts opposite to the motion of the pendulum.
3. Restoring force, the pendulum is tied at a point and the upward tension pull also tries to get the pendulum back to its original position.

Answer 18.
Manures are the source of nutrients for plants and crops growth. They are derived naturally and contain organic matter of the animal and plant wastes.
Manures are classified on the basis of kind of biological material used to prepare it as:
(1) Compost
(2) Vermicompost
(3) Green manure

1. Compost: The farm waste and livestock excreta, along with vegetable waste, sewage waste, weeds, straws etc. When allowed to decompose in a pit is called compost. The compost is rich in many nutrients.
2. Vermicompost: When the plant & animal waste matter is allowed to decompose in a pit along with some earthworms, the decomposition speeds up and is called vermicomposting. The compost prepared as a result of it is called vermicompost.
3. Green manure: Some plants like sun-hemp or guar are grown and then mulched by ploughing them into the soil. This is done before the sowing of crop seeds into the field.
   These green plants present in the soil acts as green manure which enriches the soil in nitrogen and phosphorus.

Insect pests attack the plants in three ways:

• They cut the root, stem and leaf.
• They suck the cell sap from various parts of the plant.
• They bore into the stem and fruits of plants.

In this way they affect the health of the crop and reduces the yield.

Answer 19.
(a) Mass of ball m = 200 g = 0.2 kg
Initial speed of ball u = 10 m/s
Final speed of ball v = -5 m/s
Initial momentum of the ball = mu
= 0.2 kg × 10 m/s = 2 kg m/s
Final momentum of the ball = mv
= 0.2 kg × (-5 m/s) = -1 kg m/s
Hence, change in momentum = Difference in the momentum
= – 1 – 2 = -3 kg m/s

Answer 20.
(a) The acceleration due to gravity ‘g’ is given by the formula
g = \(\frac { GM }{ { R }^{ 2 } }\), Where G = 6.67 × 10^-11 is constant

∴ The value of g on moon is 1.64 m/s², and the value of g on earth is 9.8 m/s²
Hence, the value of g on Moon is \(\frac { 1 }{ 6 }\) th of the value of g on earth.

(b) Weight of the body is given by formula

OR
Inertia: The natural tendency of an object to resist the change in their state of rest or of motion is called inertia.
The mass of an object is a measure of its inertia. Its S.I. unit is kg.
Types of inertia:
Inertia of rest: An object at rest will continue to remain at rest unless acted upon by an external unbalanced force.
Inertia of motion: An object in the state of uniform motion will continue to remain in the state of uniform motion with same speed and direction unless it is acted upon by an external unbalanced force.
Three examples of inertia in daily life are:

• When we are travelling in a vehicle and sudden brakes are applied, we tend to fall forward.
• When we shake the branch of a tree vigorously, its leaves fall down.
• If we want to remove the dust from carpet, we beat the carpet so that dust fall down.

Answer 21.
Reflection of sound waves is used in megaphones, horns and musical instruments such as trumpets and shehnais. It forms the basis of working of stethoscope used for hearing patient’s heartbeat. Ceilings of the concert halls are made curved, so that sound after reflection reaches all comers of the hall. (Any two practical applications can be written).
Bats search out its prey by emitting and detecting reflections of ultrasonic waves. The high- pitched ultrasonic squeaks of bat are reflected from the obstacles or prey and return to the bat’s ear. The nature of reflection tells the bat where the obstacle or prey is and what it is like.

SECTION-B

Answer 22.

• Appearance – Opaque
• Stability – Unstable
• Sedimentation – Sediment is formed.

Answer 23.

Answer 24.
The narrow tube B is suitable for making a stethoscope as multiple reflection is more and sound can be heard distinctly.

Answer 25.
Respiration through skin is called cutaneous respiration e.g. in Earthworm.

Answer 26.
In pressure cooker the pressure is increased. The water boils at temperature greater than 100°C.

Answer 27.
Two functions common to both roots and rhizoids are:

• absorption of water and minerals from the substrate,
• attachment of the plant body to the substrate.

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