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NEET CHEMISTRY • CLASS 11 • CHAPTER 1

Some Basic Concepts of Chemistry PYQ Mastery

Previous-year concepts को topic-wise practise करें। हर answer के बाद सिर्फ सही option नहीं—formula selection, calculation steps, common mistake और teacher-style reasoning भी समझें।

Start PYQ Practice →See study method

Attempt honestly

पहले calculation खुद करें; option देखकर guess न करें।

Check immediately

Answer submit करके step-by-step method पढ़ें।

Write the trap

Common mistake को notebook में एक line में लिखें।

Retry wrong only

अंत में “Practise wrong only” filter से weak points दोहराएँ।

REVISE BEFORE PRACTICE

One-minute formula wall

Question में numbers देखते ही पहले सही bridge formula चुनें।

Mass → Molen = given mass ÷ molar massThen particles = n × Nₐ

Gas at STPn = V ÷ 22.4 LUse only when STP convention is stated

ConcentrationM = mol/L solutionm = mol/kg solvent

FormulaMolecular = (Empirical)ₙn = molar mass/EF mass

Purity% purity = pure/sample × 100% yield = actual/theoretical × 100

DilutionM₁V₁ = M₂V₂Moles of solute stay constant

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ACCURACY0%Start your first question

QUESTION BANK40curated PYQ-pattern questions

Q1Mole Concept

NEET 2024 patternModerate

The number of molecules present in 4.4 g of CO₂ is:

Q2Mole Concept

NEET 2023 patternModerate

Which sample contains the greatest number of atoms?

Q3Mole Concept

AIPMT 2015 patternHard

Equal masses of methane and oxygen contain molecules in the ratio:

Q4Mole Concept

NEET 2022 patternModerate

At STP, 11.2 L of an ideal gas contains:

Q5Mole Concept

NEET 2021 patternHard

The total number of electrons in 3.6 g of H₂O is:

Q6Stoichiometry

NEET 2020 patternModerate

For 2H₂ + O₂ → 2H₂O, the mass of water formed from 4 g H₂ with excess O₂ is:

Q7Stoichiometry

NEET 2019 patternHard

The mass of oxygen required for complete combustion of 16 g CH₄ is:

Q8Stoichiometry

NEET 2018 patternHard

On complete combustion, 0.5 mol C₂H₆ produces how many moles of CO₂?

Q9Limiting Reagent

NEET 2025 patternHard

5 mol H₂ and 2 mol O₂ are allowed to react. The maximum amount of water formed is:

Q10Limiting Reagent

NEET 2023 patternHard

When 28 g N₂ reacts with 3 g H₂, the mass of NH₃ formed is:

Q11Limiting Reagent

AIPMT 2014 patternHard

4 mol Al reacts with 3 mol O₂ according to 4Al + 3O₂ → 2Al₂O₃. The amount of Al₂O₃ formed is:

Q12Empirical Formula

NEET 2022 patternModerate

A compound contains 40.0% C, 6.67% H and 53.33% O. Its empirical formula is:

Q13Empirical Formula

NEET 2020 patternHard

An oxide of nitrogen contains 30.4% nitrogen by mass. Its empirical formula is:

Q14Molecular Formula

NEET 2017 patternHard

A compound has empirical formula CH₂O and molar mass 180 g mol⁻¹. Its molecular formula is:

Q15Percentage Composition

NEET 2024 patternModerate

The mass percentage of oxygen in water is approximately:

Q16Percentage Composition

NEET 2021 patternHard

The percentage of nitrogen in urea, CO(NH₂)₂, is:

Q17Concentration Terms

NEET 2019 patternModerate

The molarity of a solution containing 5 mol solute in 2 L solution is:

Q18Concentration Terms

NEET 2023 patternHard

The molality of a solution made by dissolving 9.8 g H₂SO₄ in 100 g water is:

Q19Concentration Terms

NEET 2022 patternHard

The mole fraction of solute in a solution containing 1 mol solute and 4 mol solvent is:

Q20Concentration Terms

AIPMT 2016 patternHard

20% (w/w) NaOH solution means:

Q21Significant Figures

NEET 2020 patternModerate

The number of significant figures in 0.0040500 is:

Q22Significant Figures

NEET 2024 patternHard

The correctly rounded result of 12.11 + 18.0 + 1.013 is:

Q23Significant Figures

NEET 2018 patternHard

The result of 4.221 × 0.30, reported correctly, is:

Q24Laws of Combination

NEET 2019 patternModerate

The law stating that a pure compound always contains the same elements in the same mass ratio is:

Q25Laws of Combination

AIPMT 2015 patternHard

CO and CO₂ illustrate the law of:

Q26Atomic & Molecular Mass

NEET 2021 patternModerate

The formula mass of CaCO₃ is:

Q27Purity & Yield

NEET 2025 patternHard

20 g impure CaCO₃ gives 3.36 L CO₂ at STP on complete reaction with acid. The percentage purity is:

Q28Purity & Yield

NEET 2023 patternHard

The theoretical yield is 10 g but the actual yield is 8 g. Percentage yield is:

Q29Stoichiometry

NEET 2020 patternHard

The volume of O₂ at STP required to burn 5.6 L CH₄ at STP completely is:

Q30Mole Concept

NEET 2022 patternHard

One mole of electrons carries a charge closest to:

Q31Limiting Reagent

AIPMT 2013 patternHard

2 mol Na and 1 mol Cl₂ react as 2Na + Cl₂ → 2NaCl. The mass of NaCl formed is:

Q32Empirical Formula

NEET 2024 patternHard

A hydrocarbon contains 85.7% carbon and 14.3% hydrogen. Its empirical formula is:

Q33Concentration Terms

NEET 2017 patternHard

A 2 M solution is diluted from 100 mL to 500 mL. Its final molarity is:

Q34Mole Concept

NEET 2016 patternHard

The mass of one molecule of water is approximately:

Q35Stoichiometry

NEET 2025 patternHard

10 mL of a gaseous hydrocarbon needs 50 mL O₂ and gives 30 mL CO₂ at the same conditions. The hydrocarbon is:

Q36Laws of Combination

NEET 2018 patternHard

When 3 g carbon reacts with 8 g oxygen to form 11 g CO₂, the observation directly verifies:

Q37Concentration Terms

NEET 2021 patternHard

10 ppm of a solute in water approximately means:

Q38Significant Figures

NEET 2020 patternModerate

Which measurement has exactly three significant figures?

Q39Molecular Formula

NEET 2019 patternHard

Vapour density of a gas is 22. Its molar mass is:

Q40Purity & Yield

NEET 2023 patternHard

5.0 g impure CaCO₃ on heating gives 0.84 L CO₂ at STP. The sample purity is:

Academic note: Official NEET papers are published through the NTA/NEET archive. This learning set uses recurring chapter concepts and adapted/reconstructed PYQ patterns rather than claiming every sentence is a verbatim official paper. Numerical conventions follow standard NCERT-style chemistry calculations.

Some Basic Concepts of Chemistry PYQ Mastery

One-minute formula wall

Topic-wise PYQ practice

The number of molecules present in 4.4 g of CO₂ is:

Which sample contains the greatest number of atoms?

Equal masses of methane and oxygen contain molecules in the ratio:

At STP, 11.2 L of an ideal gas contains:

The total number of electrons in 3.6 g of H₂O is:

For 2H₂ + O₂ → 2H₂O, the mass of water formed from 4 g H₂ with excess O₂ is:

The mass of oxygen required for complete combustion of 16 g CH₄ is:

On complete combustion, 0.5 mol C₂H₆ produces how many moles of CO₂?

5 mol H₂ and 2 mol O₂ are allowed to react. The maximum amount of water formed is:

When 28 g N₂ reacts with 3 g H₂, the mass of NH₃ formed is:

4 mol Al reacts with 3 mol O₂ according to 4Al + 3O₂ → 2Al₂O₃. The amount of Al₂O₃ formed is:

A compound contains 40.0% C, 6.67% H and 53.33% O. Its empirical formula is:

An oxide of nitrogen contains 30.4% nitrogen by mass. Its empirical formula is:

A compound has empirical formula CH₂O and molar mass 180 g mol⁻¹. Its molecular formula is:

The mass percentage of oxygen in water is approximately:

The percentage of nitrogen in urea, CO(NH₂)₂, is:

The molarity of a solution containing 5 mol solute in 2 L solution is:

The molality of a solution made by dissolving 9.8 g H₂SO₄ in 100 g water is:

The mole fraction of solute in a solution containing 1 mol solute and 4 mol solvent is:

20% (w/w) NaOH solution means:

The number of significant figures in 0.0040500 is:

The correctly rounded result of 12.11 + 18.0 + 1.013 is:

The result of 4.221 × 0.30, reported correctly, is:

The law stating that a pure compound always contains the same elements in the same mass ratio is:

CO and CO₂ illustrate the law of:

The formula mass of CaCO₃ is:

20 g impure CaCO₃ gives 3.36 L CO₂ at STP on complete reaction with acid. The percentage purity is:

The theoretical yield is 10 g but the actual yield is 8 g. Percentage yield is:

The volume of O₂ at STP required to burn 5.6 L CH₄ at STP completely is:

One mole of electrons carries a charge closest to:

2 mol Na and 1 mol Cl₂ react as 2Na + Cl₂ → 2NaCl. The mass of NaCl formed is:

A hydrocarbon contains 85.7% carbon and 14.3% hydrogen. Its empirical formula is:

A 2 M solution is diluted from 100 mL to 500 mL. Its final molarity is:

The mass of one molecule of water is approximately:

10 mL of a gaseous hydrocarbon needs 50 mL O₂ and gives 30 mL CO₂ at the same conditions. The hydrocarbon is:

When 3 g carbon reacts with 8 g oxygen to form 11 g CO₂, the observation directly verifies:

10 ppm of a solute in water approximately means:

Which measurement has exactly three significant figures?

Vapour density of a gas is 22. Its molar mass is:

5.0 g impure CaCO₃ on heating gives 0.84 L CO₂ at STP. The sample purity is: