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Classification of Elements and Periodicity in Properties — NEET Chemistry MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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Sample questions from this chapter

What is the basis of the modern periodic law?
  1. Element properties recur periodically with atomic number ✓
  2. Element properties recur periodically with atomic mass
  3. Elements repeat their properties after every eighth position
  4. The middle member of each triad has the mean atomic mass
Answer: A. Moseley's work established atomic number as the fundamental ordering property, so modern periodicity is stated in terms of Z. Atomic mass belongs to Mendeleev's formulation.
Why not B: Atomic mass was the basis of Mendeleev's earlier law, which produced ordering anomalies.
Why not C: Newlands proposed the octave pattern, but it worked reliably only through calcium.
Why not D: Dobereiner's triad observation applied to a few groups rather than forming the modern law.
Using temporary IUPAC numerical roots, what name and symbol correspond to atomic number 120?
  1. Unnilbium, Unb
  2. Ununbium, Uub
  3. Unbinilium, Ubn ✓
  4. Unbinium, Ubi
Answer: C. The roots for 1, 2 and 0 are un, bi and nil; adding ium gives unbinilium and U-b-n gives Ubn. Digit order must be preserved.
Why not A: This reads the digits as 1-0-2 rather than the stated 1-2-0.
Why not B: Ununbium encodes 1-1-2, the old systematic construction for Z = 112.
Why not D: The zero root is nil, so the final root cannot be omitted or replaced by another un.
Which sequence correctly includes both first-ionisation exceptions in Period 2?
  1. Li < B < Be < C < O < N < F < Ne ✓
  2. Li < Be < B < C < N < O < F < Ne
  3. Ne < F < N < O < C < Be < B < Li
  4. Li < B < Be < O < C < N < F < Ne
Answer: A. The overall increase is interrupted when B begins 2p after filled 2s in Be, and when O pairs a 2p electron after half-filled N. Hence Li < B < Be < C < O < N < F < Ne.
Why not B: This follows a smooth trend and misses both exceptions: B lies below Be and O below N.
Why not C: This reverses the overall left-to-right increase while retaining neither anomaly meaningfully.
Why not D: Carbon must precede oxygen; the pairing exception lowers O below N, not below C.

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Questions

How many NEET questions are there on Classification of Elements and Periodicity in Properties?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 11 chapter.

Is this NEET Chemistry chapter test free?

Yes. Every chapter test is free with no login, and you get your all-India rank on every one. Nothing on the site is on sale right now.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.