Some Basic Concepts of Chemistry Practice Questions

Class 11 · Chemistry · 901 free MCQs with instant results and detailed explanations.

901

Total

343

Easy

419

Medium

139

Hard

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Topics in Some Basic Concepts of Chemistry

Stoichiometry 149

Mole Concept 199

Concentration 182

Atomic and Molecular Masses 371

Sample Questions from Some Basic Concepts of Chemistry

Here are 10 sample questions. Start a quiz to get randomized questions with scoring.

Easy

What is the molar mass of water (H₂O)?

A. 18 g/mol

B. 20 g/mol

C. 16 g/mol

D. 22 g/mol

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Correct Answer: A

The molar mass of water is calculated as follows: H (1 g/mol) x 2 + O (16 g/mol) = 18 g/mol.

Easy

Which of the following represents Avogadro's number?

A. 6.022 x 10²³

B. 3.14 x 10²²

C. 1.67 x 10²³

D. 9.11 x 10²²

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Correct Answer: A

Avogadro's number is defined as the number of particles in one mole of a substance, which is 6.022 x 10²³.

Easy

Which of the following is the correct unit for the amount of substance?

A. grams

B. liters

C. moles

D. micromoles

Show Answer & Explanation

Correct Answer: C

The SI unit for the amount of substance is the mole.

Medium

What is the number of particles in one mole of a substance?

A. 6.022 x 10^23

B. 3.14 x 10^22

C. 1.00 x 10^24

D. 4.68 x 10^22

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Correct Answer: A

One mole of any substance contains Avogadro's number of particles, which is 6.022 x 10^23.

Medium

Which of the following represents a solution with a high concentration of solute?

A. Dilute solution

B. Concentrated solution

C. Saturated solution

D. Unsaturated solution

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Correct Answer: B

A concentrated solution contains a large amount of solute relative to the solvent, which indicates high concentration.

Medium

In what unit is molarity expressed?

A. mol/L

B. g/L

C. mol/kg

D. L/mol

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Correct Answer: A

Molarity is defined as the number of moles of solute per liter of solution, expressed in mol/L.

Medium

What is the relationship between moles and number of molecules?

A. 1 mole = 12 molecules

B. 1 mole = 6.022 x 10^23 molecules

C. 1 mole = 100 molecules

D. 1 mole = 22.4 molecules

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Correct Answer: B

1 mole of any substance corresponds to Avogadro's number of molecules, which is 6.022 x 10^23.

Hard

What is the number of moles in 12 grams of carbon-12?

A. 1 mole

B. 0.5 moles

C. 12 moles

D. 6 moles

Show Answer & Explanation

Correct Answer: A

12 grams of carbon-12 corresponds to 1 mole, as by definition, 1 mole of a substance is equal to its molar mass in grams.

Hard

Which of the following statements about moles is incorrect?

A. 1 mole of gas occupies 22.4 L at STP

B. Moles can be used to count particles

C. Molar mass is the mass of one particle

D. Moles relate mass to the number of particles

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Correct Answer: C

Molar mass refers to the mass of one mole of a substance, not one particle.

Q10

Hard

Which of the following weighs the least?

A. 1 mole of H2

B. 1 mole of O2

C. 1 mole of N2

D. 1 mole of CO2

Show Answer & Explanation

Correct Answer: A

1 mole of H2 weighs approximately 2 g, which is less than the weights of the other gases in their mole amounts.

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Some Basic Concepts of Chemistry — Class 11 Chemistry Practice Questions Online

This page contains 901 practice MCQs for the chapter Some Basic Concepts of Chemistry in Class 11 Chemistry. The questions are organized by difficulty — 343 easy, 419 medium, 139 hard — so you can choose the right level for your preparation.

Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit. This chapter covers 4 topics, giving you comprehensive coverage of the entire chapter.