12 gm of Mg (Atomic mass = 24) will react with an acid to give:
Correct answer: C. Half mole of H2
- A. One mole of H2
- B. One mole of O2
- C. Half mole of H2
- D. Half mole of O2
Explanation
When magnesium (Mg) reacts with an acid, it typically displaces hydrogen, forming hydrogen gas (H2). The balanced chemical equation for this reaction is:Mg + 2H+ → Mg2+ + H2From this equation, we see that one mole of Mg produces one mole of H2. Since we have 12 g of Mg, which is 0.5 moles (12 g / 24 g/mol), it will produce 0.5 moles of H2 gas. Therefore, the correct answer is 'Half mole of H2'.Options A and D are incorrect because they suggest incorrect stoichiometric relationships, and Option B is incorrect because O2 is not produced in this reaction.
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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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