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DSSSB TGT Atoms and Elements — practice questions

Explore 4 free Atoms and Elements questions in DSSSB TGT Science. Open each question or exercise to read its content, reference answers and available explanation.

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Atoms and Elements questions and exercises with answers

Showing questions 1–4 of 4.

The neutron was discovered by:Read the answer and worked solution →The atomic number (Z) of an element is equal to the:Read the answer and worked solution →An atom of chlorine has atomic number Z = 17 and mass number A = 37. The number of neutrons it contains is:Read the answer and worked solution →Atoms of the SAME element with DIFFERENT mass numbers are called:Read the answer and worked solution →

Worked practice questions

The neutron was discovered by:

  1. James Chadwick in 1932
  2. J.J. Thomson in 1897
  3. Ernest Rutherford in 1911
  4. Niels Bohr in 1913
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Correct answer: A. James Chadwick in 1932

James Chadwick discovered the neutron in 1932. Thomson (1897) discovered the electron Rutherford (1911) the nucleus and proton Bohr (1913) gave the shell model.

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The atomic number (Z) of an element is equal to the:

  1. Number of neutrons inside the central nucleus
  2. Sum of protons and neutrons in the nucleus
  3. Number of electron shells in a neutral atom
  4. Number of protons inside the central nucleus
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Correct answer: D. Number of protons inside the central nucleus

The atomic number Z is defined as the number of protons in the nucleus. In a neutral atom, it also equals the number of electrons. Z defines the element uniquely.

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An atom of chlorine has atomic number Z = 17 and mass number A = 37. The number of neutrons it contains is:

  1. 17, equal to the number of its protons
  2. 20, equal to A minus Z
  3. 37, equal to the mass number A
  4. 54, equal to A plus Z
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Correct answer: B. 20, equal to A minus Z

Number of neutrons N = A - Z = 37 - 17 = 20.

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More Science topics

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