AIIMS2017Chemistry-Stoichiometry

AIIMS 2017 Chemistry Percentage Composition MCQ Question

Type: MCQ-numerical-Medium-Class 11

A sample of a mixture of CaCl2\text{CaCl}_2 and Na2CO3\text{Na}_2\text{CO}_3 weighing 4.22 g4.22\text{ g} was treated to precipitate all the Ca\text{Ca} as CaCO3\text{CaCO}_3. This CaCO3\text{CaCO}_3 is heated and quantitatively converted into 0.959 g0.959\text{ g} of CaO\text{CaO}.

Calculate the percentage of CaCl2\text{CaCl}_2 in the mixture.(Atomic mass of Ca=40\text{Ca} = 40, O=16\text{O} = 16, C=12\text{C} = 12 and Cl=35.5\text{Cl} = 35.5)

A

55.28%55.28\%

B

37.3%37.3\%

C

45.00%45.00\%

D

49.01%49.01\%

Correct Answer

Option B

Detailed Explanation

The calculation shows that 1.71 g of CaCO₃ corresponds to 189 g of CaCl₂, indicating that the mass ratio of CaCl₂ to CaCO₃ is approximately 111 g of CaCl₂ for every 100 g of CaCO₃. This results in a percentage of CaCl₂ in the mixture that is around 45%, aligning with option A. Other options are not applicable as they do not provide relevant mass ratios or percentages based on the stoichiometric relationships established in the reactions. Understanding these relationships is crucial for calculating yields and compositions in chemical reactions.

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