Chapter Exam

Unit 5: Stoichiometry — Online MCQ Test

Q: What is the SI unit of amount of substance?

Answer: B. Mole — The amount of substance is measured in mole. One mole contains Avogadro's number of entities.

Q: Which of the following is the molar mass of water (H2O)?

Answer: B. 18 g mol^-1 — Water has 2 hydrogen atoms and 1 oxygen atom, so its molar mass is 2 × 1 + 16 = 18 g mol^-1.

Q: A student has 9 g of water. How many moles of water are present? (Molar mass of H2O = 18 g mol^-1)

Answer: B. 0.50 mol — Number of moles = mass / molar mass = 9 / 18 = 0.5 mol.

Q: A compound contains 40% carbon, 6.67% hydrogen and 53.33% oxygen by mass. Its empirical formula is:

Answer: A. CH2O — Assuming 100 g, moles are C = 40/12, H = 6.67/1, O = 53.33/16, which gives a ratio close to 1:2:1. Hence the empirical formula is CH2O.

Q: For the reaction 2KMnO4 → K2MnO4 + MnO2 + O2, the sum of oxidation numbers of manganese in the products is:

Answer: D. +10 — In K2MnO4, Mn is +6 and in MnO2, Mn is +4. The sum is +6 + +4 = +10.

CHEMISTRY · CLASS 11 INTERMEDIATE 1 YEAR · Telangana State Board

Practice Unit 5: Stoichiometry with a free chapter-wise online MCQ test for Telangana State Board CLASS 11 INTERMEDIATE 1 YEAR CHEMISTRY. This chapter covers: Focusing on chemical calculations this chapter covers atomic mass mole concept equivalent weight percentage composition empirical formula and molecular formula determination. Stude.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Unit 5: Stoichiometry — Important Questions & Answers (FAQ)

Frequently asked questions from Telangana State Board CLASS 11 INTERMEDIATE 1 YEAR CHEMISTRY — Unit 5: Stoichiometry, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is the SI unit of amount of substance?

A. Gram
B. Mole ✓
C. Liter
D. Newton

Answer: B. Mole
The amount of substance is measured in mole. One mole contains Avogadro's number of entities.

Which of the following is the molar mass of water (H2O)?

A. 16 g mol^-1
B. 18 g mol^-1 ✓
C. 20 g mol^-1
D. 17 g mol^-1

Answer: B. 18 g mol^-1
Water has 2 hydrogen atoms and 1 oxygen atom, so its molar mass is 2 × 1 + 16 = 18 g mol^-1.

A student has 9 g of water. How many moles of water are present? (Molar mass of H2O = 18 g mol^-1)

A. 0.25 mol
B. 0.50 mol ✓
C. 1.00 mol
D. 2.00 mol

Answer: B. 0.50 mol
Number of moles = mass / molar mass = 9 / 18 = 0.5 mol.

A compound contains 40% carbon, 6.67% hydrogen and 53.33% oxygen by mass. Its empirical formula is:

A. CH2O ✓
B. C2H4O2
C. CH4O
D. C2H2O

Answer: A. CH2O
Assuming 100 g, moles are C = 40/12, H = 6.67/1, O = 53.33/16, which gives a ratio close to 1:2:1. Hence the empirical formula is CH2O.

For the reaction 2KMnO4 → K2MnO4 + MnO2 + O2, the sum of oxidation numbers of manganese in the products is: