Some Basic Concepts of Chemistry MCQs | Class 11 | JEE & NEET 2026
🧪 Chapter 1 · Class XI Chemistry

Some Basic Concepts
of Chemistry MCQs NCERT Chapter 1 — Class 11

Mole concept, stoichiometry, atomic & molecular mass, empirical formula, limiting reagent — the arithmetic foundations that every competitive exam builds upon. Master the calculations here; every subsequent chapter rewards you for it.

50 Questions Increasing Difficulty ~25 min NCERT-Mapped Numerical-Based Concept Boosters
📋 2026 Boards ⚡ JEE Mains 🔬 JEE Advanced 🩺 NEET
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🗓 Last Updated: February 2026 ✍️ By: Academia Aeternum Editorial Team ✅ Reviewed by: Subject Experts ⚡ Instant Feedback on Submit
🎯 Why Practice These MCQs

Some Basic Concepts of Chemistry is the compulsory gateway chapter for every competitive exam. JEE Mains repeats mole-concept numericals in almost every paper; NEET frequently pairs limiting reagent questions with concentration calculations. Students who skip this chapter's arithmetic precision consistently drop 4–8 marks across the paper — not just in this chapter.

⚛️ Mole Concept
⚖️ Stoichiometry
🧮 Limiting Reagent
📐 Empirical Formula
🔢 Atomic / Mol. Mass
💧 Concentration Units
📊 % Composition
🌡️ Significant Figures
📈 Exam Trend Analysis · Updated 2026

2024–25 JEE Mains papers showed a 35 % increase in multi-step mole calculations that chain atomic mass → moles → volume → concentration in a single question. NEET 2025 introduced two items requiring both empirical formula derivation and percentage yield in the same stem. NCERT language is preserved, but trap options now target unit-conversion errors and rounding at the intermediate step.

🎯 Knowledge Check

Chemistry — Some Basic Concepts Of Chemistry

50 Questions Class 11 MCQs
25:00 ⏱ Time
⚡ Progress 0 / 50 answered
1
Which of the following best defines chemistry?
(Class XI – Basic Concept)
2
Matter is anything that has:
(Class XI – Basic Concept)
3
Which of the following is a physical change?
(Class XI – Conceptual)
4
The SI unit of amount of substance is:
(Class XI – Fundamentals)
5
One mole of any substance contains:
(Class XI – Conceptual)
6
The mass of 1 mole of carbon-12 is:
(Class XI – Numerical)
7
Which law states that mass is conserved during a chemical reaction?
(Class XI – Laws of Chemistry)
8
The ratio by mass of elements in a compound is always:
(Class XI – Laws)
9
Which pair illustrates the law of multiple proportions?
(Class XI – Conceptual)
10
Atomic mass unit (amu) is defined relative to:
(Class XI – Fundamentals)
11
The average atomic mass of chlorine is 35.5 due to:
(Class XI – Isotopes)
12
Which of the following is an intensive property?
(Class XI – Properties of Matter)
13
Density is defined as:
(Class XI – Formula Based)
14
Which of the following is a derived SI unit?
(Class XI – Units)
15
The number of significant figures in 0.00520 is:
(Class XI – Significant Figures)
16
Which measurement is most precise?
(Class XI – Data Analysis)
17
The empirical formula represents:
(Class XI – Conceptual)
18
If the empirical formula mass equals molecular mass, the formula is:
(Class XI – Conceptual)
19
Molar mass of \(H_2SO_4\) is:
(Class XI – Numerical)
20
The percentage of oxygen in water is approximately:
(Class XI – Numerical)
21
One mole of any gas at STP occupies:
(Class XI – Gas Concept)
22
The number of moles in 44 g of \(CO_2\) is:
(Class XI – Numerical)
23
Which quantity has no unit?
(Class XI – Conceptual)
24
Molarity depends on:
(Class XI – Conceptual)
25
Molality is expressed as:
(Class XI – Formula)
26
Which is more reliable at varying temperatures?
(Class XI – Application)
27
Limiting reagent determines:
(Class XI – Stoichiometry)
28
In a reaction, theoretical yield is:
(Class XI – Conceptual)
29
Percentage yield is calculated as:
(Class XI – Formula)
30
The dimensional formula of density is:
(Class XI – Advanced Basics)
31
If 2 moles of \(NaOH\) react with 1 mole of \(H_2SO_4\), the balanced equation is:
(Class XI – Stoichiometry)
32
Which has the maximum number of atoms?
(Class XI – Comparative)
33
The smallest mass is of:
(Class XI – Numerical Concept)
34
A solution containing 1 mol solute in 1 L solution is:
(Class XI – Concentration)
35
The term stoichiometry refers to:
(Class XI – Conceptual)
36
Which error affects accuracy but not precision?
(Class XI – Experimental)
37
The mass percent of solute is:
(Class XI – Formula)
38
Which quantity remains unchanged on dilution?
(Class XI – Conceptual)
39
Avogadro’s law relates:
(Class XI – Gas Laws)
40
The volume occupied by 0.5 mol of gas at STP is:
(Class XI – Numerical)
41
Which is a state function?
(Class XI – Conceptual)
42
The mole fraction of solvent in a dilute solution is:
(Class XI – Reasoning)
43
The limiting reagent is the reactant:
(Class XI – Application)
44
Which measurement has highest relative error?
(Class XI – Numerical Reasoning)
45
The formula mass of \(NaCl\) refers to:
(Class XI – Ionic Compounds)
46
The term “significant figures” indicates:
(Class XI – Measurement)
47
Which conversion factor is correct?
(Class XI – Units)
48
The smallest unit that retains chemical identity is:
(Class XI – Fundamentals)
49
If empirical formula is \(CH_2\) and molar mass is 42 g mol\(^{-1}\), molecular formula is:
(Class XI – Advanced Numerical)
50
Stoichiometric coefficients in a balanced equation represent:
(NEET/JEE – Conceptual)

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