KENDRIYA VIDYALAYA STEEL PLANT - CLASS IX SCIENCE SAMPLE PAPER
SET - A (Total Marks: 40)
Section A: MCQs (10 x 1 = 10 Marks)
1. Who identified the sub-atomic particle called 'electron'?
B) J.J. Thomson
C) Neils Bohr
D) John Dalton
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Answer: B (J.J. Thomson)
2. Atomic radius is measured in which unit?
B) Millimetres
C) Nanometres
D) Centimetres
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Answer: C (Nanometres)
3. The ratio of the mass of hydrogen to oxygen in water is always:
B) 8:1
C) 1:2
D) 2:1
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Answer: A (1:8)
4. Which of these elements is monoatomic?
B) Helium
C) Hydrogen
D) Chlorine
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Answer: B (Helium)
5. The electronic configuration of a Sodium atom (Z=11) is:
B) 8, 2, 1
C) 2, 1, 8
D) 2, 8, 2
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Answer: A (2, 8, 1)
6. The SI unit of the Universal Gravitation Constant (G) is:
B) N m²/kg²
C) m/s²
D) N kg/m²
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Answer: B (N m²/kg²)
7. The value of acceleration due to gravity (g) on Earth is:
B) 10.8 m/s²
C) 6.7 m/s²
D) 8.9 m/s²
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Answer: A (9.8 m/s²)
8. 1 Joule is defined as:
B) 1 kg × 1 m/s
C) 1 W × 1 s
D) 1 N / 1 m²
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Answer: A (1 N × 1 m)
9. The power of an agent that does 1 Joule of work in 1 second is:
B) 1 Newton
C) 1 Watt
D) 1 Henry
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Answer: C (1 Watt)
10. What is the chemical symbol for Iron?
B) I
C) Fe
D) In
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Answer: C (Fe)
Section B: Case Based Questions (2 x 4 = 8 Marks)
Case 1: Rutherford's Alpha-Particle Scattering Experiment.
Rutherford selected a gold foil about 1000 atoms thick. Fast-moving alpha particles (doubly-charged helium ions) were made to fall on it. He expected minor deflections but observed that most particles passed straight, while some deflected by large angles and 1 in 12,000 rebounded.
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2. What are alpha particles? Ans: They are doubly-charged helium ions with a mass of 4 u.
3. What was the "incredible" observation in the experiment? Ans: One out of every 12,000 particles appeared to rebound.
4. What did the "rebound" indicate about the atom? Ans: It showed that all positive charge and mass were concentrated in a tiny volume (nucleus).
Case 2: Scientific Conception of Work.
In science, work is defined based on specific conditions. For example, pushing a pebble that moves involves work. However, pushing a huge rock that stays stationary, or standing still with a heavy load, does not count as scientific work.
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2. What are the two conditions for work to be done? Ans: A force should act on the object and the object must be displaced.
3. If force is in the direction of displacement, is work positive or negative? Ans: It is taken as positive.
4. Give the formula for work. Ans: Work = Force × displacement (W = Fs).
Section C: Match the Following (4 x 1 = 4 Marks)
| Column A | Column B |
|---|---|
| 1. Canal Rays | A. J. Chadwick |
| 2. Neutron | B. E. Goldstein |
| 3. Isotopes | C. James Watt |
| 4. Power | D. Same Z, Different A |
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Answer: 1-B, 2-A, 3-D, 4-C
Section D: Short Answer Questions (5 x 2 = 10 Marks)
1. Define Valency.
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The combining power or capacity of an element is known as its valency.
It is determined by the number of valence electrons gained, lost, or shared to complete an octet.
2. State the Law of Conservation of Mass.
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Mass can neither be created nor destroyed in a chemical reaction.
During a reaction, the sum of the masses of reactants and products remains unchanged.
3. Define Atomic Number.
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Atomic number is defined as the total number of protons present in the nucleus of an atom.
It is denoted by the symbol ‘Z’ and defines the identity of an element.
4. Distinguish between mass and weight.
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Mass is a measure of an object's inertia and remains constant everywhere.
Weight is the force of attraction of the earth on an object and changes based on location.
5. What is kinetic energy?
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Kinetic energy is the energy possessed by an object due to its motion.
It increases with the speed of the object and is calculated as ½mv².
Section E: Long Answer Questions (2 x 4 = 8 Marks)
1. Describe the postulates of Bohr’s model of an atom.
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1. Only certain special discrete orbits of electrons are allowed inside the atom.
2. While revolving in these discrete orbits, the electrons do not radiate energy.
3. These orbits or shells are called energy levels and are represented as K, L, M, N....
4. Electrons are distributed in these shells according to the formula 2n².
2. State Archimedes’ Principle and list two of its applications.
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Principle: When a body is immersed in a fluid, it experiences an upward force equal to the weight of the fluid displaced.
App 1: It is used in designing ships and submarines to ensure they float.
App 2: It is used in lactometers to determine the purity of milk samples.
App 3: It is used in hydrometers to determine the density of various liquids.
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