Some Basic Concepts of Chemistry

Some Basic Concepts of Chemistry

Question

How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mole of oxygen atoms?

  • 0.02

  • 3.125 × 10–2

  • 1.25 × 10–2

  • 2.5 × 10–2

Answer

B.

3.125 × 10–2

Mg subscript 3 left parenthesis PO subscript 4 right parenthesis subscript 2
apostrophe straight n apostrophe space moles
8 straight n space equals space 0.25
straight n space equals space fraction numerator 0.25 over denominator 8 end fraction
space equals space fraction numerator 25 over denominator 8 space straight x space 100 end fraction space equals space 3.125 space straight x space 10 to the power of negative 2 end exponent

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