ACME ACADEMY

WEEKLY EVALUATION TEST

Subject: Science
Time Limit: 20 Mins
Max Marks: 20 Marks
Student Name:
Roll Number:
Class / Sec:
Date:

GENERAL INSTRUCTIONS:

  1. All questions are compulsory. Carefully read all instructions before starting.
  2. The question paper contains 20 questions.
  3. There is no negative marking for incorrect answers.
  4. Use of mobile phones, smartwatches, or calculators is strictly prohibited during the exam.
1. Which ancient Indian philosopher proposed that matter could be divided into the smallest indivisible particles called 'parmanus'?
[1 Mark]
(A) Aryabhata
(B) Sushruta
(C) Acharya Kanada
(D) Charaka
2. J.J. Thomson discovered the electron by studying the conduction of electric current through gases at low pressure. What were the streams of negatively charged particles emitted in his experiment called?
[1 Mark]
(A) Alpha rays
(B) Gamma rays
(C) Cathode rays
(D) X-rays
3. In Thomson's 'plum pudding' model, how are the charges within an atom arranged?
[1 Mark]
(A) Electrons orbit a dense, positively charged nucleus.
(B) The atom is a sphere of positive charge with negatively charged electrons distributed throughout it.
(C) Protons and neutrons are packed tightly in the centre, with electrons on the outside.
(D) The atom is completely empty space with no charges.
4. During Rutherford's gold foil experiment, why did a few alpha particles bounce back sharply?
[1 Mark]
(A) Because they hit the loosely bound electrons in the gold atoms.
(B) Because gold is a very heavy, solid metal.
(C) Because all the positive charge and mass of an atom are densely concentrated in a tiny central region called the nucleus.
(D) Because the alpha particles were negatively charged and repelled by electrons.
5. What was the major limitation of Rutherford's planetary model of the atom?
[1 Mark]
(A) It failed to account for the presence of neutrons.
(B) It could not explain why a continuously accelerating electron wouldn't lose energy and spiral into the nucleus, causing the atom to collapse.
(C) It assumed atoms were entirely solid.
(D) It could not explain the emission of cathode rays.
6. According to Niels Bohr's model, how do electrons revolve around the nucleus without losing energy?
[1 Mark]
(A) They move freely in random, zig-zag paths.
(B) They continuously exchange energy with protons.
(C) They revolve only in fixed, allowed circular paths called stationary states or energy levels.
(D) They remain completely stationary at all times.
7. Using the formula 2n^2, what is the maximum number of electrons that can be accommodated in the M-shell (where n=3)?
[1 Mark]
(A) 2
(B) 8
(C) 18
(D) 32
8. Which subatomic particle, discovered by James Chadwick in 1932, resides in the nucleus, has a mass nearly equal to a proton, but carries no electrical charge?
[1 Mark]
(A) Positron
(B) Electron
(C) Alpha particle
(D) Neutron
9. The atomic number of an element is strictly defined by the number of which particles in its nucleus?
[1 Mark]
(A) Electrons
(B) Neutrons
(C) Protons
(D) Nucleons
10. An atom of sodium has an atomic number of 11 and a mass number of 23. How many neutrons does this atom have?
[1 Mark]
(A) 11
(B) 12
(C) 23
(D) 34
11. The electronic configuration of carbon (atomic number 6) is 2, 4. To become stable, carbon usually:
[1 Mark]
(A) Loses 4 electrons.
(B) Gains 6 electrons.
(C) Shares 4 electrons with other atoms to complete its octet.
(D) Does not react because it is already stable.
12. The three isotopes of hydrogen are protium, deuterium, and tritium. What is the fundamental structural difference between them?
[1 Mark]
(A) They have different numbers of protons.
(B) They have different numbers of electrons.
(C) They have different numbers of neutrons.
(D) They belong to completely different elements.
13. Assertion (A): The chemical properties of all isotopes of a given element are exactly the same. Reason (R): Isotopes have the same number of electrons and the same electronic configuration.
[1 Mark]
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true, but R is false.
(D) A is false, but R is true.
14. Why is the average atomic mass of naturally occurring chlorine exactly 35.5 u instead of a whole number?
[1 Mark]
(A) Because a chlorine atom is cut in half.
(B) Because it is calculated as a weighted average of its two naturally occurring isotopes (Cl-35 and Cl-37) based on their relative abundances in nature.
(C) Because it has exactly 18.5 neutrons.
(D) Because the mass of an electron is factored in.
15. Atoms of different elements, like Argon (atomic number 18) and Calcium (atomic number 20), can both have a mass number of 40. What are such atoms called?
[1 Mark]
(A) Isotopes
(B) Isomers
(C) Isobars
(D) Ions
16. Which specific radioactive isotope is commonly used in medical radiation treatment for cancer?
[1 Mark]
(A) Carbon-14
(B) Uranium-235
(C) Cobalt-60
(D) Iodine-131
17. Which rule correctly describes the arrangement of electrons in the outermost shell of an atom according to Bohr and Bury?
[1 Mark]
(A) The outermost shell can accommodate a maximum of 18 electrons.
(B) The outermost shell can accommodate a maximum of 8 electrons (except if it's the first shell, which holds 2).
(C) Electrons are filled randomly in any shell.
(D) Outer shells are filled before the inner shells.
18. If a symbol for an element is written as ^14_6C, what does the number '6' signify?
[1 Mark]
(A) The mass number
(B) The number of neutrons
(C) The atomic number (number of protons)
(D) The valency
19. Heavier elements like uranium (92 protons) have significantly more neutrons than protons (146 neutrons). What is the primary role of these extra neutrons in a heavy nucleus?
[1 Mark]
(A) To balance the negative charge of the electrons.
(B) To reduce the electrostatic repulsion between the positively charged protons and increase the strong nuclear force, keeping the nucleus bound together.
(C) To increase the atomic number of the element.
(D) To absorb all the electrons from the inner shells.
20. In the modern IUPAC nomenclature of elements, how should the symbol for the element 'Cobalt' be correctly written?
[1 Mark]
(A) CO
(B) cb
(C) Co
(D) co
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