Some Basic Concepts of Chemistry Class 11 Case Study Questions Chemistry Chapter 1

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Last Updated on April 20, 2025 by XAM CONTENT

Hello students, we are providing case study questions for class 11 Chemistry. Case study questions are the new question format that is introduced in CBSE board. The resources for case study questions are very less. So, to help students we have created chapterwise case study questions for class 11 Chemistry. In this article, you will find case study questions for cbse class 11 Chemistry chapter 1 Some Basic Concepts of Chemistry.

Chapter	Some Basic Concepts of Chemistry
Type of Questions	Case Study Questions
Nature of Questions	Competency Based Questions
Board	CBSE
Class	11
Subject	Chemistry
Useful for	Class 11 Studying Students
Answers provided	Yes
Difficulty level	Mentioned
Important Link	Class 11 Chemistry Chapterwise Case Study

Case Study Questions on Some Basic Concepts of Chemistry

Case Study Question 1:

Passage:
A chemist is working with a sample of carbon dioxide gas. She takes exactly 44 g of $\mathrm{CO}_2$ and wants to determine the number of molecules present in the sample. She knows the molar mass of $\mathrm{CO}_2$ is $44 \mathrm{~g} / \mathrm{mol}$, and Avogadro’s number is $6.022 \times 10^{23} \mathrm{~mol}^{-1}$. She plans to use this information to carry out further stoichiometric calculations.

Q1. What is the number of moles of $\mathrm{CO}_2$ in the sample?
(a) 1 mol
(b) 2 mol
(c) 0.5 mol
(d) 4 mol

Answer: (a)
Explanation:
Moles $=$ mass $/$ molar mass $=\frac{44}{44}=1 \mathrm{~mol}$

Q2. How many molecules of $\mathrm{CO}_2$ are present in the sample?
(a) $6.022 \times 10^{22}$
(b) $6.022 \times 10^{24}$
(c) $3.011 \times 10^{23}$
(d) $6.022 \times 10^{23}$

Answer: (d)
Explanation:
1 mole contains Avogadro’s number of molecules $=6.022 \times 10^{23}$

Q3. If the chemist doubles the mass of $\mathrm{CO}_2$ to 88 g , what will be the number of oxygen atoms in the new sample?
(a) $1.2044 \times 10^{24}$
(b) $2.4088 \times 10^{23}$
(c) $2 \times 6.022 \times 10^{23}$
(d) $6.022 \times 10^{23}$

Answer: (a)
Explanation:
– ” $88 \mathrm{~g}=2 \mathrm{~mol} \mathrm{CO}{ }_2$ “
– “Each molecule has 2 oxygen atoms”
– “Total oxygen atoms $=2 \times 2 \times 6.022 \times 10^{23}=2.4088 \times 10^{24}$ “

Case Study Question 2:

Passage:
In a laboratory, a reaction between 5 g of hydrogen gas $\left(\mathrm{H}_2\right)$ and 40 g of oxygen gas $\left(\mathrm{O}_2\right)$ is carried out to produce water using the reaction:

$$
2 \mathrm{H}_2+\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O}
$$

The chemist wants to find out which reactant is limiting and how much water will be produced.
Q1. What is the number of moles of $\mathrm{H}_2$ in 5 g ? (Molar mass $=2 \mathrm{~g} / \mathrm{mol}$ )
(a) 5 mol
(b) 2.5 mol
(c) 10 mol
(d) 1 mol

Answer: (b)
Explanation:

$$
\text { Moles }=\frac{5}{2}=2.5 \mathrm{~mol}
$$

Q2. What is the number of moles of O₂ in 40 g? (Molar mass = 32 g/mol)
(a) 2 mol
(b) 1.25 mol
(c) 1 mol
(d) 3 mol

Answer: (a)
Explanation:

$$
\text { Moles }=\frac{40}{32}=1.25 \mathrm{~mol}
$$

Q3. Which is the limiting reagent and how many moles of water are formed?
(a) H₂; 2.5 mol
(b) O₂; 2.5 mol
(c) O₂; 2 mol
(d) H₂; 2 mol

Answer: (d)
Explanation:
From balanced equation:
$2 \mathrm{~mol} \mathrm{H}_2$ reacts with $1 \mathrm{~mol} \mathrm{O}_2 \rightarrow 2 \mathrm{~mol} \mathrm{H}_2 \mathrm{O}$
Available: $2.5 \mathrm{~mol} \mathrm{H}_2$ and $1.25 \mathrm{~mol} \mathrm{O}_2$
Required $\mathrm{H}_2$ for $1.25 \mathrm{~mol} \mathrm{O}_2=2.5 \mathrm{~mol} \rightarrow$ Both are in perfect ratio
So neither is limiting, but assuming small changes, $\mathrm{H}_2$ is fully consumed to give $2.5 \mathrm{~mol} \mathrm{H}_2 \Rightarrow 2.5 \mathrm{~mol} \mathrm{H}_2 \mathrm{O}$

We hope the given case study questions for Some Basic Concepts of Chemistry Class 11 helps you in your learning.

Also check

• Chemical Thermodynamics Class 11 Case Study Questions Chemistry Chapter 5
• Chemical Bonding and Molecular Structure Class 11 Case Study Questions Chemistry Chapter 4
• Classification of Elements and Periodicity in Properties Class 11 Case Study Questions Chemistry Chapter 3
• Structure of Atom Class 11 Case Study Questions Chemistry Chapter 2
• Some Basic Concepts of Chemistry Class 11 Case Study Questions Chemistry Chapter 1

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Topics from which case study questions may be asked

• Laws of chemical combination
• Mole concept
• Molar mass
• Stoichiometry

The concept of a mole allows chemists to count particles by weighing them — a foundational idea in Chemistry.

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