CBSE Sample Papers for Class 9 Science Paper 3

CBSE Sample Papers for Class 9 Science Paper 3 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 3.

CBSE Sample Papers for Class 9 Science Paper 3

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 3 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.
Two balls of different masses is thrown vertically upwards, which one will rise to greater height?

Question 2.
State the significance of membrane biogenesis.

Question 3.
Which cell organelle are called suicidal bags of the cell and why?

Question 4.
What is meant by concentration of a solution? A solution contains 50 g common salt in 350 g of water. Calculate the concentration of the solution.

Question 5.
Give two properties of colloid.

Question 6.
Which accident will be more fatal, collision between two cars moving at same speed of 60 km/h, or a two trucks moving with the same speed of 60 km/h. Explain.

Question 7.
Give the differences between collenchyma and sclerenchyma tissues.

Question 8.
A hammer of mass 500 g moving at 50 ms^-1, strikes a nail. The nail stops the hammer in a very short period of time equal to 0.01 s. What is the force of the nail on the hammer?

Question 9.
Compare the use of manures and fertilisers in maintaining the fertility of soil.

Question 10.
Give the characteristics of Aves.
OR

1. Identify two features possessed by all Chordates.
2. In which class would you place any organism which has
   1. a scaly exoskeleton and a bony endoskeleton
   2. a scaly exoskeleton and lay eggs outside water.

Question 11.
A substance ‘X’ on heating gives Y and Z. What is X – An element or a compound? State two differences between an element and a compound.

Question 12.
(a) State Newton’s first law of motion.
(b) Look at the diagrams given below and answer the following questions:

In which case will the object move and in which direction? Give reason in support of your answer.
OR

State Newton’s universal law of gravitation. Express it mathematically. Mention any two phenomena which were explained on the basis of this law.

Question 13.
List any six desirable agronomic characteristics for crop improvement.

Question 14.
Discuss with the help of suitable examples three ways in which microorganisms can find entry into human body.

Question 15.

1. Write chemical formula of Aluminium Sulphate.
2. Give one example each of a homo-diatomic & homo-tetratomic molecule.

Question 16.

1. Define evaporation. Out of nylon and cotton clothes, which will be more comfortable during summers and why?
2. Is evaporation and boiling are same? If not, why?

Question 17.

1. What are genetically modified crops?
2. Name four factors for which variety improvement is done.
3. Write any two ways to control weeds.

Question 18.

1. Define Inertia. Name the physical quantity that measures it.
2. While alighting from a bus it is necessary to run along with the moving bus in the same direction of the bus. Give reason.
3. Calculate the magnitude of force required to produce an acceleration of 2 m/s² in a body of mass 12.5 kg.

Question 19.

1. Illustrate Rutherford’s experiment to explain the model of an atom.
2. Atomic number of an element is 17. Identify the element, write its electronic configuration & mention its valency.

Question 20.
With the help of a labelled diagram show the cycling of carbon in nature. What are the two ways in which carbon-dioxide is fixed in the environment.
OR
Explain the importance of ozone to mankind.

Question 21.
How are cultivation practices and crop yield related to weather? Describe any three factors for which variety improvement is done.

SECTION-B

Question 22.
What are infrasound and ultrasound?

Question 23.
Stare two precautions while measuring the volume in the cylinder.

Question 24.
Give two functions of osmosis.

Question 25.
A measuring cylinder has 5 marks between 10 mL to 20 mL. What is its least count?

Question 26.
What is the function of bulbs present in monocot roots?

Question 27.
To make a solution, 40 g of common salt is dissolved in 280 g of water. Calculate its concentration in terms of mass by mass percentage of the solution.

Answers
SECTION-A

Answer 1.
The ball with lower mass will rise up to a greater height.

Answer 2.
It helps in building up of cell, in tissue culture, in the field of agriculture and genetic engineering.

Answer 3.
Lysosomes are called suicidal bags; as they contain digestive enzymes which can digest organic materials and can also digest a poorly working cell on its own.

Answer 4.
The concentration of a solution is the amount of solute present in a given amount of solution.
Mass of solution (salt) = 50 g
Mass of solvent (water) = 350 g
Total mass of solution = 400 g
Concentration = \((\frac { 50 }{ 400 } )\) × 100 = 12.5 %

Answer 5.

• The particles are very small and cannot be seen with naked eyes.
• Colloidal solutions are stable and shows Tyndall effect.

Answer 6.

• Two trucks moving with the speed of 60 km/h will produce more momentum than the two cars moving with same speed due to the larger mass of trucks.
• Hence collision between two trucks will have more impact and is thus more fatal.

Answer 7.

Answer 8.
Mass of hammer, m = 500 g = 0.5 kg
Initial velocity of hammer, u = 50 ms^-1
Final velocity of hammer, v = 0 and time, t = 0.01 s

-ve sign of the force suggests that the force is opposing the motion of hammer.
∴ Force applied by the nail on hammer = 2500 N

Answer 9.
Effects of using manures on soil quality:

• Manures enrich the soil with nutrients and provide a lot of organic matter (humus) to the soil and thus restores water retention capacity of sandy soils and drainage capacity in clayey soil.
• The addition of manures reduces the chances of soil erosion.
• They provide food for the soil organisms, like soil friendly bacteria.

Effects of using fertilisers on soil quality:

• By continuous use of fertilisers, soil can become powdery, dry and the chances of soil erosion increases.
• By the use of fertilisers, the organic matter decreases which further decreases the porosity of soil and plant roots planted in the soil do not get oxygen properly.
• The nature of soil turns to acidic or basic unnecessarily and it can harm the soil organisms.

Answer 10.

• Aves/birds can fly.
• Hollow and light bones.
• Streamlined body and forelimbs are modified into wings.
• Warm-blooded animals, heart with four chambers.
• Egg laying animals.
• Beaks present, teeth are absent.

OR

1. Presence of notochord/ dorsal nerve chord/ paired gill pouches/ have a bilaterally symmetrical body/ are triploblastic/ are coelomate. (any two)
2. 1. Class pisces
   2. Class Reptilia

Answer 11.
As, X on heating gives two new substances Y and Z.
Therefore, X is a compound

1. Elements are made up of only one kind of atoms like gold, iron while compounds are made up of two or more kinds of atoms combined together in a definite proportion.
2. Elements cannot be broken down into simpler substances by chemical reactions. However, compound during chemical reaction can break into simpler substances.

Answer 12.
(a) Every object in this universe continues to be in its state of rest or of uniform motion in a straight line, unless acted upon by some external unbalanced force to change that state.
(b) Case I: Object will remain static because of equal and opposite forces acting upon it.
Case II: Object will move towards left in the direction of 25 N force. This is because an unbalanced force of 25 – 15 = 10 N is acting in this direction.
OR

Every object in this universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of distance between them. This force is along the line joining the centres of the two objects.
F = G.\(\frac { Mm }{ { d }^{ 2 } } \)
Where F = Force; Mm = Product of two masses
d = Distance between the centres of two objects
G = Universal Gravitation constant = 6.67 × 10^-11 Nm² kg^-2
Phenomena which were explained on the basis of universal law of Gravitation:

• The force that binds us to the earth.
• The motion of moon around the earth.
• The motion of planets around the sun.
• The formation of tides due to the moon and the sun. (any two)

Answer 13.

• High yield
• Improved quality
• Biotic and abiotic resistance.
• Change in maturity duration.
• Wider adaptability.
• Desirable agronomic characteristics.
• Development of novel varieties, (any six)

Answer 14.

• Through cuts and wounds (Tetanus)
• Through contaminated food and water (Cholera)
• Through sexual contact (AIDS, Syphillis)
• Through air (TB, Pneumonia)
• Through direct skin contact (Ring worm) (any three)

Answer 15.

1. Aluminium sulphate:
   
2. Homo-diatomic molecule – O₂/H₂/N₂
   Homo-tetratomic molecule – P₄.

Answer 16.

1. The change in the state of matter from liquid to gas is called evaporation.
   Cotton is a good absorber of water than that of Nylon. So, during summers cotton clothes absorb sweat, which on evaporation causes cooling effect to the body.
2. They are not exactly the same. Boiling of liquid takes place at its boiling point, whereas evaporation can occur at any temperature or room temperature. Evaporation is a surface phonemenon while boiling is a bulk phenomenon.

Answer 17.
1. Genetically modified crop: In this method, a gene that would provide the desired characteristics is introduced into the crop. The crop so obtained is called genetically modified crop.
2. Some of the factors for which crop variety improvement is done are:

1. Higher Yield: Variety improvement has been done to increase the productivity of the crop per acre of cultivated land. This is very important in order to meet the food demand for rapidly growing population.
2. Improved Quality: The definition of quality is different for different crops, e.g. baking quality is important in wheat, protein quality in pulses, oil quality in oil seeds and preserving qualities in fruits and vegetable.
3. Wider Adaptability: Varieties that can grow under any condition and can adapt themselves to various environmental conditions, help in stabilising the crop production.
4. Biotic and Abiotic Resistance: Biotic factors like (pathogens, insects and nematodes) and abiotic factors (drought, salinity, water logging, heat cold and frost) affects crop production to a great extent. Varieties resistant to such factors are always preferred and improves the crop production.

3. Two ways to control weeds:

1. Preventive methods: Proper seed bed preparation, timely sowing of crops, intercropping and crop rotation.
2. Chemical methods: Spraying of herbicides or weedicides, e.g. Atrazine 2, 4 – D.

Answer 18.

1. It is the tendency of a body to remain in its state of rest or of uniform motion in a straight line. Quantity that measure it is mass.
2. While alighting from the moving bus, the feet of the person will suddenly come to rest while rest of the body is in the state of motion due to inertia of motion and hence the person may fall down and may get injured.
3. a = 2 m/s²; m= 12.5 kg
   F = m × a
   = 2 × 12.5 = 25 N

Answer 19.
1. Rutherford’s scattering experiment: He selected a very thin gold foil to be bombarded with fast moving α-particles – which are doubly positively charged ‘He’ ions.
The fast moving a-particles have a considerable amount of K. E. to hit the gold atoms.
Observations:

• Most of the α-particles passed straight through the foil without any deflection.
• One out of 12,000 particles appeared to rebound.

Inference:

• There is a positive centre inside the atom at the centre, called nucleus.
• The electrons revolve around the nucleus in well defined orbits.
• The size of the nucleus is very small as compared to the size of the atom.

2. Atomic number is 17
Element is chlorine 1
Electronic configuration – 2, 8, 7; valency – 1

Answer 20.
(a)

(b)

• By the conversion of CO₂ into glucose by green plants in the presence of sunlight during photosynthesis.
• Usage of carbonates dissolved in sea-water by marine animals to make their shells.

OR

• Ozone is a molecule of oxygen with three atoms of oxygen, O₃.
• It covers the Earth’s atmosphere and is present in the stratosphere. It does not allow the harmful ultra-violet radiations coming from the sun to reach our Earth surface.
• These ultra-violet radiations cause ionising effect, can cause cancer and genetic disorder in any life-forms.
• The ozone is getting depleted at the south pole near Antartica. The ozone depletion is due to the halogens like CFC (chlorofluorocarbon) released in the air.
• Chlorine and fluorine reacts with the ozone and splits it, thereby leading to formation of a big hole called ozone hole.
• Thus, we need to protect the ozone layer from getting depleted by reducing the consumption of fossil-fuels and other factors which leads to the depletion of ozone layer.
  

Answer 21.
Different crops require different climatic conditions, temperature and photoperiods for their growth. Photoperiods are related to sunlight and ultimately with weather. Some crops grow well in rainy season (Kharif crops) while others grow well in winter season (Rabi crops).
Also, because weather conditions such as occurence of droughts and flood situations are unpredictable, varieties that can be grown in diverse climatic conditions are useful.
Factors (any three):

• Higher yield
• Improved quality
• Biotic and Abiotic resistance
• Change in maturity
• Wider adaptability
• Desirable agronomic characteristics.

SECTION-B

Answer 22.

• The sound waves with frequency less than 20 Hz is called infrasound.
• The sound waves with frequency higher than 20 kHz is called ultrasound.

Answer 23.

1. The measuring cylinder should be placed on a plain flat surface.
2. The lower meniscus and eyeline should be parallel.

Answer 24.

1. Plant root cells absorb water by osmosis.
2. The unicellular organisms like amoeba takes in the required material by osmosis.

Answer 25.
20 mL – 10 mL = 10 mL
∵ 5 × 2 = 10
Each mark is of 2 mL value.

Answer 26.

• The fibrous roots in monocot plants are short, gives less nutrient to the plant, during spring when leaves are shed.
• Bulbs present in the roots of monocot plants store food and supply it to the plant.

Answer 27.
Mass of solute = 40g
Mass of solvent = 280 g
Mass of solution = Mass of solute + Mass of solvent
= 40 g + 280 g
= 320 g
Mass percentage of solution

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