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Some Basic Concepts of Chemistry — 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

Which observation identifies a sample as a mixture rather than a pure compound?
  1. Its components can occur in variable proportions and be separated by physical methods ✓
  2. Its constituent elements occur in a fixed mass ratio
  3. Every particle has the same chemical composition
  4. Its components lose their individual properties through chemical bonding
Answer: A. A mixture has variable composition and its components retain enough identity for physical separation. The closest trap is the fixed-ratio statement, which describes a compound, not a homogeneous mixture.
Why not B: A fixed elemental mass ratio is characteristic of a pure compound under the law of definite proportions.
Why not C: Identical chemical particles describe a pure substance rather than a mixture.
Why not D: Chemical bonding creates a compound; mixture components retain their identities and can often be separated physically.
A liquid has density 2.50 g cm^-3. What is this density in kg m^-3?
  1. 2.50 kg m^-3
  2. 250 kg m^-3
  3. 2.50 × 10^3 kg m^-3 ✓
  4. 2.50 × 10^4 kg m^-3
Answer: C. 1 g cm^-3 = (10^-3 kg)/(10^-6 m^3) = 10^3 kg m^-3. Therefore 2.50 g cm^-3 equals 2.50 × 10^3 kg m^-3.
Why not A: This changes the unit labels without applying either the gram-to-kilogram or cubic-centimetre-to-cubic-metre factor.
Why not B: This applies a factor of 100, as though the centimetre conversion were linear rather than cubic.
Why not D: This uses a net factor of 10^4, commonly produced by cubing 100 but mishandling the 10^-3 gram-to-kilogram conversion.
An iron oxide contains 69.9% Fe and 30.1% O by mass. What is its empirical formula? Use Fe = 55.85 and O = 16.00.
  1. Fe2O3 ✓
  2. FeO
  3. FeO3
  4. Fe3O2
Answer: A. In 100 g, Fe gives 69.9/55.85 = 1.252 mol and O gives 30.1/16.00 = 1.881 mol. Division by 1.252 gives 1:1.50; doubling both terms yields Fe2O3.
Why not B: FeO results from rounding the calculated O:Fe mole ratio of about 1.50 directly to 1 instead of clearing the half by multiplying both ratios by 2.
Why not C: FeO3 results from converting 1.50 to 3 for oxygen but failing to multiply the iron ratio by the same factor of 2.
Why not D: Fe3O2 reverses the correctly cleared Fe:O ratio of 2:3.

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Questions

How many NEET questions are there on Some Basic Concepts of Chemistry?

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.