Class 9 Science: Sample Question Paper Term II- 2 (With Solutions) | Science Class 9 PDF Download

Class - IX

General Instructions:

1. All questions are compulsory.
2. The question paper has three sections and 15 questions. All questions are compulsory.
3. Section–A has 7 questions of 2 marks each; Section–B has 6 questions of 3 marks each; and Section–C has 2 case based questions of 4 marks each.
4. Internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.

Q.1: Atomic numbers of two elements A and B are given below.
Atomic number of element A:  18, Atomic number of element B: 17
(a) Which element  has zero valency?
(b) What is the valency of other element ? 

(a) Element A has zero valency because electronic configuration of element A is 2, 8, 8 i.e., a complete octet.
(b) The atomic number of element B= 17, i.e., it has 17 electrons. Hence, its electronic configuration will be 2, 8, 7.
Since it has 7 electrons in its valence shell, so, its valency = 8 – 7= 1

Q.2: Two students of class IX are discussing a law that states the mass of reactants is always equal to that of the products.
(a) Identify the law.
(b) Based on the above law find out if 12 g of carbon is burnt in the presence of 32 g of oxygen, how much carbon dioxide will be formed?

(a) Law of conservation of mass: The law states that matter can neither be created nor be destroyed or mass of reactants is always equal to that of product.
(b) C + O₂ → CO₂
Carbon + Oxygen → Carbon dioxide
Mass of reactants = 12 + 32 = 44g
Mass of product (CO₂) = 44 g
Thus, one mole of Carbon (C) reacts with one mole of Oxygen (O₂) to form one mole of CO₂.
So, 1 mole of CO₂ is formed.

Q.3:  An atom of an element has three electrons in its 3rd orbit, which is the outermost shell. Write:
(a) (i) the electronic configuration (ii) atomic number
(b) (i) number of protons (ii) valency

(a) (i) Electronic configuration: 2, 8, 3
(ii) Atomic number: 13
(b) (i) Number of protons: 13

(ii) Valency: 3

Q.4: During a health survey in a locality, it was found that some children fall ill more frequently than others living in the same locality. 

(a) Is this a sign of good immune system? Explain.

(b) Is this a sign of good personal hygiene? Justify your statement.

(a) No, it is not a sign of good immune system. Only some children fall ill means they have less resistance to diseases which is due to poor immune system.
(b) No, personal hygiene is important to develop resistance against diseases. If the children are falling ill frequently, it means that they might be neglecting health and hygiene.

Q.5: Although Archana has been suffering from cold and cough she decided to appear for her class test. Classmates seated close to her had an exposure to the infection being carried by Archana. However, only one of them actually suffered from cold and cough.
(a) Which system is responsible for fighting with infection carrying microbes?
(b) What prevented the rest of those classmates from catching cold and cough in spite of their exposure to the infection.

OR

“Making antiviral medicines is harder than making antibacterial medicines”. Justify this statement.

(a) Immune system of an individual fight from infection carrying microbes.
(b) Immune system of those who does not suffer with cold and cough successfully fought against the microbes to which they were exposed.

OR

Viruses have very few biochemical mechanisms of their own. They depend on their host to complete all the biochemical reaction. Thus, it is very difficult to find the targets where these drugs get interfered by not making any harm to the host.

Q.6: A box of about 10 kg is placed at a point A on a horizontal surface. It is moved to a point B which is at a distance of 2 m from A by the action of force, 4N applied on the box at an angle of 60^o.
(a) Find the work done by the gravitational force on the box.

(b) Calculate the work done by the externally applied force.
Justify your answer. (Given, g = 10 m/s2)

OR

You might have seen that when a blacksmith hits a sheet of iron by fast-moving hammer, the iron sheet heats up.
(a) Which type of energy does the fast-moving hammer possess?
(b) State the type of energy conversion that takes place in the above process.

(a) Work done is zero because force due to gravity is perpendicular to the displacement that occurred due to applied external force.
W = F_gd cos 90° = 0 J
[∴ cos 90° = 0, F_g = Force due to gravity]
(b) Given, m= 10 kg
Work done = F.d cos 60^o
= 4 × 2 × ½
=4 J

OR

(a) Kinetic energy
(b) The kinetic energy get converted into heat energy during hitting a metal by a fast moving hammer due to which metal gets heated.

Q.7: Force is the push or pull upon an object which results due to its interaction with another object. This force is directly proportional to the mass of the object on which it acts. Depending on these facts, teacher has asked Rajat to explain what will happen to the force between two objects A and B if:
(a) The mass of one object is doubled?
(b) The distance between the objects is tripled? Help Rajat to find the answers.

OR

The given table shows value of 'g' at equator and at poles. It is seen that it differs at the equator and on poles.

Name the positions on the Earth where the value of 'g' is (i) maximum (ii) minimum. State the reason for this difference.

Force due to gravitational pull, F = Gm₁m₂/d², As force is directly proportional to masses and inversely proportional to the square of distance between them, then
(a) If m₁ = 2m, then F becomes twice.
(b) If d  = 3d₁, then F becomes one-ninth.

OR

On earth, value of g is maximum at poles and minimum at the equator.
At poles, radius of earth is less so the value of g is more than on equator, at equator radius of earth is more so, value of g is less. It is because, g ∝ 1/(R²)

Q.8: As a part of practical examination paper, Nisha has to classify the following elements on the basis of their valencies. But she could not recollect what is valency and what is cation. Help her to answer the below questions. 
(a) Define valency.
(b) Define cation.
(c) Classify the following cations on the basis of their valencies : NH₄⁺ , Al⁺⁺⁺

(a) The combining power (or capacity) of an element to displace or combine with number of hydrogen atoms is known as its valency.
(b) Cation- Ion with positive electric charge.
(c) NH₄⁺ → Monovalent
Al⁺⁺⁺ → Trivalent

Q.9: Show the formation of chemical formulae of the following compounds using their ions :
(a) (i) Ammonium sulphate  (ii) Magnesium nitrate
(b) Interpret the number of moles of oxygen atoms in PO₄^3-

OR

(a) Which postulate of Dalton’s atomic theory is the basis of law of conservation of mass ?
(b) Write the name of compounds represented by the following formulae : 
(i) KNO₃ (ii) Al₂(SO₄)₃ (iii) CCl₄ (iv) H₂S.

(a) (i)

(ii)

(b) Each mole of phosphate ion possesses 4 moles of oxygen atoms as represented by the formula.

OR

(a) Atom can neither be created nor destroyed.
(b) (i) Potassium nitrate
(ii) Aluminium sulphate
(iii) Carbon tetrachloride
(iv) Hydrogen sulphide

Q.10: Given that the percentage abundance of the isotope ₁₀Ne²⁰ is 90% and that of isotope ₁₀Ne²² is 10%. Calculate the average atomic mass of Neon.

Average atomic mass is given by:
20 x 90/100 + 22 x 10/100
= (18 + 2.2)u
= 20.2u

Q.11: (a) From the symbol ₁₆S³² state:
(i) Atomic number of sulphur
(ii) Mass number of sulphur
(iii) Electronic configuration of sulphur
(b) Which of the two elements given below would be chemically more reactive, 'X' of atomic number 18 or element 'Z' of atomic number 16 and why?

(a) (i) 16 (ii) 32 (iii) ₁₆S = 2, 8, 6
(b) Z is more reactive than X. This is because, electronic configuration of Z = 2, 8, 6 which may gain 2 electrons and thus is more reactive whereas X = 2, 8, 8 has complete octet and is inert.

Q.12: State the law of conservation of energy. With the help of an example explain the law of conservation of energy.

OR

An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the total work done against the force of gravity and by the force of gravity on the object? Explain with proper mathematical expressions.

Energy can neither be created nor destroyed but it can be transformed from one form to the another.
Explanation of law of conservation of energy : Let us take the example of simple pendulum. We draw a pendulum bob to one side and allow it to oscillate.
The pendulum bob has P. E. at the extreme positions. Then, it is converted to K.E. at the mean position and so on.
It comes to rest due to air resistance and friction with the hook. Energy is lost in overcoming friction and air resistance. But total energy remains constant.

OR

(i) Work done = mgh
Difference in height of initial and final position is zero.

Q.13: (a) Differentiate between mass and weight.
(b) The weight of a body at a height equal to be radius of the earth is ‘N’. What will be its weight at a height equal to three times the radius of the earth?

(a) Any condition which impairs the health, or interferes with the normal functioning of the body is called disease.
(b) A symptom is a phenomenon that is experienced by the individual affected by the disease.
(c) Causes :
(i) Extrinsic factor : Water, food.
(ii) Intrinsic factor : Poor eating habits, poor nourishment.
(iii) Genetic constitution : Weak immune system.
(iv) Social reason : Poor public services.

Q.14: Read the passage and answer the following questions.
We know that food is necessary for the growth and development of the body. It provides the necessary components such as proteins, carbohydrates and fats which are required for proper functioning of the body.
Justify the following statements:
(a) "Availability of proper and sufficient food would prevent from infectious diseases".
(b) Balanced diet is necessary for maintaining healthy body.
(c) Health of an organism depends upon the surrounding environmental conditions.

OR

Our surrounding areas should be free of stagnant water.

(a) Availability of proper and sufficient food is one of the measure to prevent the occurrence of the infectious diseases. As the infectious diseases also spread through the food we eat; thus, if we obtain healthy and nutritious food, free of germs causing diseases, it would definitely prevent us from catching the infection.
(b) Yes, balanced diet provides raw materials and energy in appropriate amount in the form of protein, carbohydrates, fats, minerals, etc., which, in turn, are essential for the proper growth and functioning of the healthy body.
(c) Yes, health is a state of being well enough to function well physically, mentally and socially, and these conditions depend upon the surrounding environmental conditions. e.g., if there is an unhygienic condition in the surrounding area, it is likely we might get infected or diseased.

OR

Yes, this is so because many water-borne diseases and insect vectors flourish in stagnant water which causes diseases in human beings.

Q.15: An experiment based on simple pendulum was conducted in a class. The following diagram shows the set up. It shows a simple pendulum consisting of a bob of mass 100 g. Initially the bob of the pendulum is at rest at ‘O’. It is then displaced to one side at A. The height of ‘A’ above ‘O’ is 5 cm. (Take g = 10 m/s²)

(a) What is the value of potential energy of bob at ‘A’ ?
(b) What is the value of kinetic energy of the bob at mean position ‘O’ ?
(c) What is the value of kinetic energy and potential energy of the bob at the position ‘P’ whose height above mean position is 2 cm ?

OR

The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy ? Why ?

(a) Given, m = 100 g = 0.1 kg; g = 10 m/s²
The value of potential energy of the bob at 'A' = m × g × h
= 0.1 × 10 × 0.05 = 0.05 J
(b) At mean position , total P.E. change to K.E. So, kinetic energy of the bob at mean position = 0.05 J.
(c) P.E. at 2 m height = m×g×h
= 0.1 × 10 × 0.02
= 0.02 J
K.E. at 2 m height = Total energy – P.E. at 2 m height
= 0.05 – 0.02 = 0.03 J

OR

The law of conservation of energy states that energy can neither be created nor be destroyed, but can be converted from one form to another.

The given condition does not violate the law. This is because potential energy is converted into kinetic energy.