An element M forms a hydride MH3 which contains 90% of M by mass. What is the relative atomic mass of M?
Correct answer: A. 27
- A. 27
- B. 30
- C. 87
- D. 90
Explanation
To calculate the relative atomic mass of M, we can use the fact that the hydride MH3 contains 90% of M by mass.Let the atomic mass of M be x. Then, the mass of M in one molecule of MH3 is x/3, and the mass of H in one molecule of MH3 is (3 x 1.008) = 3.024.Since the hydride MH3 contains 90% of M by mass, we can write:mass of M in MH3 / total mass of MH3 = 0.9(x/3) / (x/3 + 3.024) = 0.9Solving this equation, we get x = 27. Therefore, the relative atomic mass of M is 27.
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