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UP Board Class 10 Periodic Classification of Elements — practice questions

Explore 50 free Periodic Classification of Elements questions in UP Board 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 radius of the $n$-th Bohr orbit of a hydrogen-like atom of atomic number $Z$ varies as:Read the answer and worked solution →The minimum energy required to remove an electron from the ground state of a hydrogen atom is:Read the answer and worked solution →The kinetic energy of an electron in the $n$-th Bohr orbit of a hydrogen atom is related to its total energy $E_n$ by:Read the answer and worked solution →Which spectral series of hydrogen lies entirely in the ultraviolet region?Read 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 →Why are the noble gases very stable chemically?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 radius of the $n$-th Bohr orbit of a hydrogen-like atom of atomic number $Z$ varies as:

  1. $r \propto n / Z^2$
  2. $r \propto Z / n^2$
  3. $r \propto n^2 / Z$
  4. $r \propto Z n^2$
Show answer and solution

Correct answer: C. $r \propto n^2 / Z$

From Bohr's derivation, $r_n = \dfrac{n^2 h^2}{4\pi^2 m k Z e^2}$, hence $r_n \propto n^2 / Z$. **Therefore higher orbits are larger ($n^2$) and higher-$Z$ atoms hold their electrons in tighter orbits ($1/Z$).**

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