Chemistry Stoichiometry MDCAT 2018
PMDC Verified Question 85 of 105
3.0 mole of calcium will contain ____ g of calcium.
A
105gm
B
80gm
C
100gm
D
120gm
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 120gm
Concept:

The mass of a macroscopic sample can be found directly if the number of moles and the molar mass of the substance are known.

Formula:

$$ m = n \times M $$

Solution:

  • The chemical symbol for Calcium is Ca.


  • The molar mass (M) of Calcium is exactly \( 40 \text{ g/mol} \).


  • We are given \( n = 3.0 \text{ moles} \).


  • Multiply moles by the molar mass: \( m = 3.0 \text{ moles} \times 40 \text{ g/mol} \).


  • Result: \( 120 \text{ g} \).


Why other options are incorrect:

  • 105gm, 80gm, 100gm: These values result from multiplying 3.0 by incorrect arbitrary atomic mass values (such as 35, 26.6, or 33.3).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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