NEET Chemistry: Chemical equations and stoichiometry Practice Questions
13 free multiple-choice questions on Chemical equations and stoichiometry (Some Basic Concepts in Chemistry) for NEET Chemistry, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. Which quantity is conserved in any chemical reaction, according to the Law of Conservation of Mass?
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Correct answer: A — Mass of products
The Law of Conservation of Mass states that the total mass of the reactants must equal the total mass of the products in a closed system.
Q2. What is the definition of a mole in stoichiometry?
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Correct answer: A — The amount of substance containing 6.022 × 10²³ particles
One mole is the SI unit for the amount of substance. It represents the number of entities (atoms, molecules, ions, etc.) present in 6.022 × 10²³ particles, known as Avogadro's number.
Q3. If the molar mass of an element is M, the mass of n moles of that element is given by which expression?
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Correct answer: C — n × M
The mass of a substance is calculated by multiplying the number of moles (n) by its molar mass (M). Mass = n × M.
Q4. If 1 mole of an element has a molar mass of 30 g/mol, what is the mass of 1 mole of that element?
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Correct answer: A — 30 g
By definition, if the molar mass is 30 g/mol, then 1 mole of that substance has a mass of 30 g.
Q5. When 16 grams of carbon reacts completely with 16 grams of oxygen to form carbon dioxide, what is the mass of carbon dioxide formed? (Assume all mass is conserved)
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Correct answer: B — 32 grams
According to the Law of Conservation of Mass, the total mass of reactants equals the total mass of products. Mass of CO₂ formed = Mass of C + Mass of O = 16 g + 16 g = 32 g.
Q6. If 5 moles of reactant A are required to produce 1 mole of product B in a reaction, how many moles of product B are produced when 10 moles of reactant A are used?
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Correct answer: C — 2 moles
The stoichiometric ratio is 5 moles A → 1 mole B. If we use 10 moles of A, the ratio is 10/5 = 2. Therefore, 2 × 1 mole B = 2 moles of B will be produced.
Q7. In a reaction where 10 moles of Reactant A react with 15 moles of Reactant B, what is the mole ratio of A to B consumed?
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Correct answer: C — 2:3
The mole ratio of A to B consumed is 10 moles of A : 15 moles of B. Simplifying this ratio by dividing both by 5 gives 2:3.
Q8. Which principle dictates that mass is neither created nor destroyed during a chemical reaction?
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Correct answer: A — Law of Conservation of Mass
The Law of Conservation of Mass states that the total mass of the reactants must equal the total mass of the products in any closed chemical reaction.
Q9. In the balanced chemical equation 2H₂ + O₂ → 2H₂O, what do the coefficients (2, 1, 2) signify?
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Correct answer: C — The ratio of reactants and products
The coefficients in a balanced chemical equation represent the mole ratios of the reactants and products involved in the reaction.
Q10. If 1 mole of a substance reacts completely with 2 moles of another substance according to a chemical equation, what is the mole ratio of the first substance to the second substance?
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Correct answer: C — 2:1
If 1 mole reacts with 2 moles, the ratio of moles is 1:2.
Q11. If 1 mole of hydrogen gas reacts completely with 1 mole of oxygen gas to produce water, what is the mole ratio of H₂ to O₂ in the reaction?
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Correct answer: A — 1:1
From the balanced equation H₂ + O₂ → H₂O, the stoichiometric coefficients are both 1, meaning the mole ratio of H₂ to O₂ is 1:1.
Q12. If the molar mass of an element is 30 g/mol, what is the mass of 2 moles of that element?
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Correct answer: B — 60 g
Mass is calculated by multiplying the number of moles by the molar mass. Mass = moles × molar mass. So, 2 moles × 30 g/mol = 60 g.
Q13. For the balanced chemical equation P₄ + O₂ → P₂O₅, if 1 mole of P₄ is reacted with 1 mole of O₂, how many moles of P₂O₅ are produced?
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Correct answer: C — 2 moles
The stoichiometric ratio from the balanced equation is 1:1. Therefore, 1 mole of P₄ reacts with 1 mole of O₂ to produce 1 mole of P₂O₅.
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