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DSSSB TGT Atoms — practice questions

Explore 42 free Atoms questions in DSSSB TGT Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Atoms questions and exercises with answers

Showing questions 1–30 of 42.

Who first proposed in ancient India that matter is made of indivisible particles called parmanus?Read the answer and worked solution →Cathode rays, discovered by J.J. Thomson in 1897, are streams of:Read the answer and worked solution →The gold foil experiment of Geiger and Marsden (under Rutherford, 1911) used what particles to bombard the foil?Read the answer and worked solution →In Rutherford's planetary model, the nucleus is approximately how much smaller than the atom?Read the answer and worked solution →In which year was radioactivity discovered, providing the first evidence that atoms are NOT indivisible?Read the answer and worked solution →A neutral atom has equal numbers of:Read the answer and worked solution →Which of the following statements correctly orders the historical development of atomic models?Read the answer and worked solution →The atomic NUMBER of an element equals the number of:Read the answer and worked solution →The mass NUMBER of an atom equals:Read the answer and worked solution →Atoms of the same element with different mass numbers (i.e., different numbers of neutrons) are called:Read the answer and worked solution →For an atom with atomic number 6 (Carbon), the number of electrons in a NEUTRAL atom is:Read the answer and worked solution →The MAXIMUM number of electrons that can occupy the second shell (L shell) is:Read the answer and worked solution →Sodium has 11 electrons. Its electron configuration (electrons in K, L, M shells) is:Read the answer and worked solution →Chlorine has 17 electrons. To become STABLE (achieve octet in outermost shell), it most easily:Read the answer and worked solution →The element Fluorine has 9 protons and 10 neutrons. The mass number and atomic number are respectively:Read the answer and worked solution →An atom of Magnesium loses 2 electrons. The resulting Mg²⁺ ion has the same electron configuration as which noble gas?Read the answer and worked solution →Order the atomic models as they were proposedRead the answer and worked solution →Match each scientist to their modelRead the answer and worked solution →Match each model to what it could NOT explainRead the answer and worked solution →True or false: Rutherford's modelRead the answer and worked solution →True or false: Bohr's modelRead the answer and worked solution →Complete the reason Bohr's model failsRead the answer and worked solution →Which model does this belong to?Read the answer and worked solution →Match each quantum number to what it is calledRead the answer and worked solution →True or false: the quantum mechanical modelRead the answer and worked solution →Order the structure: from atom down to electronRead the answer and worked solution →Complete the (n + l) ruleRead the answer and worked solution →True or false: orbital energiesRead the answer and worked solution →Match each rule to what it forbids or requiresRead the answer and worked solution →Tap every statement Hund's rule requiresRead the answer and worked solution →

Worked practice questions

Who first proposed in ancient India that matter is made of indivisible particles called parmanus?

  1. Sushruta
  2. Acharya Kanada
  3. Aryabhata
  4. Charaka
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Correct answer: B. Acharya Kanada

Acharya Kanada (~6th century BCE) proposed in his Vaisesika Sutras that if matter (dravya) is repeatedly divided, you reach the smallest indivisible particles — parmanus. This was one of the earliest atomistic theories, paralleling Greek thinkers Leucippus and Democritus.

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Cathode rays, discovered by J.J. Thomson in 1897, are streams of:

  1. Negatively charged particles (later called electrons)
  2. Light photons
  3. Positive particles
  4. Neutral atoms
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Correct answer: A. Negatively charged particles (later called electrons)

Thomson found that cathode rays deflect toward the positive plate in an electric field — meaning they carry NEGATIVE charge. They have a much smaller mass than any atom. These particles are called electrons. Their discovery proved that atoms have internal structure.

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The gold foil experiment of Geiger and Marsden (under Rutherford, 1911) used what particles to bombard the foil?

  1. Gamma rays
  2. Neutrons
  3. Beta particles
  4. Alpha particles
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Correct answer: D. Alpha particles

Geiger and Marsden aimed alpha particles (helium-4 nuclei, He²⁺) at a thin gold foil. Most passed through, a few were deflected at large angles, and a very small fraction bounced back almost directly. This pattern was inconsistent with Thomson's plum-pudding model.

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