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Chemistry

Some Basic Concepts of Chemistry

A Chemistry chapter of the NEET syllabus, and how to practise it for the computer-based exam.

Exam rules change between cycles. Confirm dates, syllabus and pattern against NTA's official site. We are not NTA.

Weightage: what the paper actually did

Some Basic Concepts of Chemistry carried 4 questions in the NEET 2026 paper. One paper is a data point, not a destiny: NTA moves weight between chapters every cycle, which is why the weightage tables deserve care. The stable facts are the paper's shape: 180 questions, 720 marks, +4 right, −1 wrong.

Sample PYQs from this chapter

Real questions NTA asked from Some Basic Concepts of Chemistry, with the answer and the working. Try before you peek.

Question 1 · NEET 2026

The number of hydrogen atoms present in 5.4 g of urea is: (Given: Molar mass of urea = 60 g mol−160\ \text{g mol}^{-1}; NA=6.022×1023 particles mol−1N_A = 6.022 \times 10^{23}\ \text{particles mol}^{-1})
  1. A.1.084×10231.084 \times 10^{23}
  2. B.1.084×10221.084 \times 10^{22}
  3. C.2.168×10222.168 \times 10^{22}
  4. D.2.168×10232.168 \times 10^{23}
Answer and explanation

Answer: D

Moles of urea = 5.4/60 = 0.09 mol. Urea, NH2CONH2\mathrm{NH}_{2}\mathrm{CONH}_{2}, contains 4 hydrogen atoms per molecule. So number of H atoms = 0.09 * 4 * 6.022 * 102310^{23} ≈\approx 2.168 * 102310^{23}. The distractors arise from using the wrong number of H atoms per molecule or a wrong power of ten.

Question 2 · NEET 2026

The numbers 17.0145 and 21.0235 were rounded to three figures after the decimal point. The resulting numbers, respectively, are
  1. A.17.014 and 21.023
  2. B.17.015 and 21.023
  3. C.17.014 and 21.024
  4. D.17.015 and 21.024
Answer and explanation

Answer: C

Both numbers end in an exact 5 with nothing after it, which is the tie case, so the round-half-to-EVEN convention applies rather than always rounding up. In 17.0145 the digit to be retained is 4, already even, so it stays: 17.014. In 21.0235 the retained digit is 3, which is odd, so it is raised to the even value 4: 21.024. NCERT Class 11, Some Basic Concepts of Chemistry (significant figures).

How to practise Some Basic Concepts of Chemistry

Chapter by chapter, against real past-paper questions, on a screen: NEET is computer based from 2027. Read the chapter once, then attempt its PYQs until your accuracy stops climbing, and let the wrong answers tell you which lines to reread. If the chapter keeps refusing to stick, that has its own guide. There is also a free NEET mini mock with answers.

Nearby Chemistry chapters

Questions

How many questions did Some Basic Concepts of Chemistry have in NEET 2026?

Some Basic Concepts of Chemistry carried 4 questions in the NEET 2026 paper. Weightage shifts between cycles, so treat it as a probability, not a promise.

Where can I practise Some Basic Concepts of Chemistry PYQs for NEET?

Explore available chapter-wise NEET practice in BrainIt, free until the 2027 exam. Review explanations and track chapter accuracy to guide your revision. Sample questions from this chapter are on this page.

Is Some Basic Concepts of Chemistry important for NEET 2027?

It is part of the Chemistry syllabus the paper draws from, and NEET 2027 is computer based, so practise it on a screen. Your own accuracy in the chapter matters more than any weightage table: a heavy chapter you already score well on needs less time than a light one you keep missing.

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