Unit 5: Stoichiometry — Online MCQ Test
CHEMISTRY · CLASS 11 INTERMEDIATE 1 YEAR · Telangana State Board
Practice Unit 5: Stoichiometry with a free chapter-wise online MCQ test.
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....
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Unit 5: Stoichiometry — Important Questions & Answers
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.
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.
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.
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.
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:
- A. +7
- B. +6
- C. +4
- D. +10
Answer: D. +10
In K2MnO4, Mn is +6 and in MnO2, Mn is +4. The sum is +6 + +4 = +10.
In K2MnO4, Mn is +6 and in MnO2, Mn is +4. The sum is +6 + +4 = +10.