A sample of an iron and oxygen ore has a mass of 35.8 grams. The iron in the compound has a mass of 27.9 grams. What is the percent iron in the ore?
Correct answer: D. 78% Fe
- A. 74% Fe
- B. 75% Fe
- C. 77% Fe
- D. 78% Fe
Explanation
Percentage of iron = (mass of iron ÷ mass of ore) x 100 = (27.9 g ÷ 35.8 g) x 100 = 77.93%, which rounds to 78% Fe. Thus option d is correct. The closest alternative is c, 77% Fe, usually chosen when the decimal result is truncated instead of rounded.
Last updated
About Moles and Avogadro's Number
The mole connects the microscopic number of particles with measurable mass, using Avogadro's number, 6.022 × 10²³ particles per mole. Questions involve molar mass, conversion between mass, moles and particles, percentage composition, empirical and molecular formulas, and distinguishing atoms, molecules, ions and formula units.
Practise Fundamental Concepts of Chemistry
894 free Fundamental Concepts of Chemistry MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Chemistry questions like this
Chemistry is on 12 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
0.5 mole of nitrogen gas and 0.5 mole of carbon monoxide gas at STP have same_____________?
1 a.m.u =__________________?
1 amu is equal to 1.661 x 10^-24g, then 1.0 g will be equal to:
1 molar solution of glucose in water contains weight of glucose________________?
10 L of Cl2 gas reacts with 40L of H2 gas under same condiitions of temperature and pressure. How much volume of HCl should be produced?