Caffeine (molecular weight = 194) contains 28.9% nitrogen. The number of nitrogen atoms in caffeine molecule is:
Correct answer: B. 4
- A. 2
- B. 4
- C. 7
- D. 8
Explanation
Mass of nitrogen in 194 amu caffeine N= 28.9gN= 28.9 /100N= 28.9/100 x194 ∴ One molecule of caffeine will contain =56 /14 which is equal to 4 nitrogen atoms
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About Fundamental Concepts of Chemistry
Mole calculations connect mass, number of particles and Avogadro's number, while balanced equations provide the mole ratios used in stoichiometry. Questions cover limiting and excess reactants, theoretical yield and percentage yield, including identifying which reactant is consumed first and comparing the actual product with the maximum possible product.
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