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CBSE Class 10 Periodic Classification of Elements — practice questions

Explore 50 free Periodic Classification of Elements questions in CBSE Class 10 Science. Open each question or exercise to read its content, reference answers and available explanation.

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Periodic Classification of Elements questions and exercises with answers

Showing questions 1–30 of 50.

Which of the following arrangements is in correct order of increasing electronegativity (Pauling scale)?Read the answer and worked solution →The element with electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^3$ belongs to which group and period?Read the answer and worked solution →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 →CLASS10 · Chemistry · Periodic Table Trends — Gap FillRead the answer and worked solution →CLASS10 · Chemistry · Periodic Classification — Group NamesRead the answer and worked solution →Sort: down a group, what happens? (CBSE Cl 10)Read the answer and worked solution →Match the group to its property (CBSE Cl 10)Read the answer and worked solution →Who put forward the law of triads?Read the answer and worked solution →Newlands' law of octaves stated that every:Read the answer and worked solution →Mendeleev arranged elements primarily in order of:Read the answer and worked solution →The modern periodic table is based on:Read the answer and worked solution →How many periods does the modern periodic table have?Read the answer and worked solution →What is the valency of an element with electronic configuration 2, 8, 3?Read the answer and worked solution →Atomic radius generally DECREASES across a period because:Read the answer and worked solution →Which is the most reactive metal?Read the answer and worked solution →Which property INCREASES on going down a group?Read the answer and worked solution →Which element has the highest electronegativity in the periodic table?Read the answer and worked solution →How does metallic character change down a group?Read the answer and worked solution →Sodium (atomic number 11) belongs to which group and period?Read the answer and worked solution →Which of the following has the largest atomic radius?Read the answer and worked solution →Which trend is followed by ionisation energy across a period?Read the answer and worked solution →Which set lists representative elements (s-block and p-block) only?Read the answer and worked solution →Which pair shows the diagonal relationship in the periodic table?Read the answer and worked solution →Across period 3, which element forms the most acidic oxide?Read the answer and worked solution →Why is potassium more reactive than sodium?Read the answer and worked solution →How does the size of a cation compare with its parent atom?Read the answer and worked solution →Which is the most non-metallic element of group 16?Read the answer and worked solution →

Worked practice questions

Which of the following arrangements is in correct order of increasing electronegativity (Pauling scale)?

  1. F < O < N < C
  2. N < C < O < F
  3. C < N < O < F
  4. O < F < N < C
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Correct answer: C. C < N < O < F

Electronegativity increases across a period and decreases down a group. The Pauling-scale values for period 2 nonmetals: - C: 2.55 - N: 3.04 - O: 3.44 - F: 3.98 (highest of any element) So the correct ascending order is **C < N < O < F**. Option A reverses everything. Option C breaks the trend by putting F before O. Memory aid: "FONClBrISCHP" is the electronegativity ladder from highest to lowest among common nonmetals (F first, P last among this set).

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The element with electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^3$ belongs to which group and period?

  1. Group 13, Period 3
  2. Group 15, Period 4
  3. Group 2, Period 4
  4. Group 17, Period 4
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Correct answer: B. Group 15, Period 4

**Period** equals the highest principal quantum number, which is 4 here. So Period 4. **Group**: the outermost shell ($n=4$) has $4s^2 4p^3$. For p-block elements, group number = 10 + (number of $s$ valence + number of $p$ valence) = 10 + (2 + 3) = **15**. This configuration matches **arsenic (As)**, atomic number 33. Check: As is below P and N in group 15 (nitrogen family), period 4. ✓

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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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