Class JEE Chemistry ALL Q #1171
COMPETENCY BASED
APPLY
4 Marks 2026 JEE Main 2026 (Online) 21st January Morning Shift MCQ SINGLE
Consider the following reaction: $Ca+2HCl \rightarrow CaCl_2+H_2$. If 14g of calcium reacts with excess HCl, choose the incorrect option.
(A) Mass of $CaCl_2$ produced is 38.85 g
(B) Moles of $H_2$ produced is 0.35 mol
(C) Volume of $H_2$ produced at STP is 7.84 L
(D) Mass of $CaCl_2$ produced is 3.885 g
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Step-by-Step Solution

  1. Step 1: Calculate the moles of Calcium (Ca)

    The molar mass of Ca is 40 g/mol.

    Moles of Ca = Mass of Ca / Molar mass of Ca = 14 g / 40 g/mol = 0.35 mol

  2. Step 2: Determine the moles of $CaCl_2$ and $H_2$ produced

    From the balanced equation, $Ca + 2HCl \rightarrow CaCl_2 + H_2$, 1 mole of Ca produces 1 mole of $CaCl_2$ and 1 mole of $H_2$.

    Therefore, 0.35 mol of Ca will produce 0.35 mol of $CaCl_2$ and 0.35 mol of $H_2$.

  3. Step 3: Calculate the mass of $CaCl_2$ produced

    The molar mass of $CaCl_2$ is 40 + 2(35.5) = 40 + 71 = 111 g/mol.

    Mass of $CaCl_2$ = Moles of $CaCl_2$ * Molar mass of $CaCl_2$ = 0.35 mol * 111 g/mol = 38.85 g

  4. Step 4: Calculate the volume of $H_2$ produced at STP

    At STP, 1 mole of any gas occupies 22.4 L.

    Volume of $H_2$ = Moles of $H_2$ * 22.4 L/mol = 0.35 mol * 22.4 L/mol = 7.84 L

  5. Step 5: Analyze the options

    • (A) Mass of $CaCl_2$ produced is 38.85 g - Correct
    • (B) Moles of $H_2$ produced is 0.35 mol - Correct
    • (C) Volume of $H_2$ produced at STP is 7.84 L - Correct
    • (D) Mass of $CaCl_2$ produced is 3.885 g - Incorrect

Correct Answer: D

AI Suggestion: Option D

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires students to apply their knowledge of stoichiometry and mole concepts to calculate the mass, moles, and volume of products in a chemical reaction.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to apply a series of steps (a procedure) to arrive at the solution, including calculating moles, using stoichiometric ratios, and applying the ideal gas law (or molar volume at STP).
Syllabus Audit: In the context of JEE, this is classified as COMPETENCY. It assesses the student's ability to apply stoichiometric principles to a given chemical reaction and determine the quantities of reactants and products. This goes beyond simple recall and requires problem-solving skills.

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