38 year neet pyq , mole concept

 

Past 38 Years NEET/AIPMT PYQs on Some Basic Concepts of Chemistry (Mole Concept)

Welcome to our comprehensive collection of previous year questions (PYQs) from the topic "Some Basic Concepts of Chemistry" — primarily covering Mole Concept, Stoichiometry, Limiting Reagent, Molar Mass, Empirical & Molecular Formula etc. These questions have appeared in NEET/AIPMT exams from 1988 to 2024. Each question is followed by a detailed solution and the year in which it was asked.

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🔹 NEET/AIPMT 1988–1995: PYQs with Solutions

(1988–1995 questions already listed)

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🔹 NEET/AIPMT 1996–2005: PYQs with Solutions

(1996–2005 questions already listed)

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🔹 NEET/AIPMT 2006–2024: PYQs with Solutions

19. [AIPMT 2006]
Calculate number of atoms in 1.6 g of oxygen gas.

Solution:
O2 mol = 1.6 / 32 = 0.05 mol
Molecules = 0.05 × 6.022×10²³ = 3.011×10²²
Atoms = 2 × 3.011×10²² = 6.022×10²²
Answer: 6.022×10²² atoms

20. [AIPMT 2007]
What is the molar mass of a compound if 0.5 mol weighs 29 g?

Solution:
Molar mass = 29 g / 0.5 mol = 58 g/mol
Answer: 58 g/mol

21. [AIPMT 2008]
0.5 mol of which of the following contains maximum number of atoms?
Options: H2O, CH4, NH3, C2H6

Solution:
0.5 mol × number of atoms per molecule:
H2O (3), CH4 (5), NH3 (4), C2H6 (8)
→ C2H6 has max atoms: 0.5×8×6.022×10²³ = 2.409×10²⁴
Answer: C2H6

22. [AIPMT 2009]
Mass of 0.5 mol O2 gas is?

Solution:
M = 0.5 × 32 = 16 g
Answer: 16 g

23. [AIPMT 2010]
How many moles are present in 8 g of NaOH?

Solution:
Molar mass = 40 → mol = 8/40 = 0.2 mol
Answer: 0.2 mol

24. [AIPMT 2011]
What is the number of molecules present in 1.7 g of NH3?

Solution:
Molar mass = 17 → mol = 1.7/17 = 0.1 mol
Molecules = 0.1 × 6.022×10²³ = 6.022×10²²
Answer: 6.022×10²²

25. [NEET 2012]
How many atoms of oxygen are present in 0.5 mol of Al2(SO4)3?

Solution:
Each formula = 12 O atoms → Total = 0.5 × 6.022×10²³ × 12 = 3.613×10²⁴
Answer: 3.613×10²⁴

26. [NEET 2013]
Calculate molar mass of compound X if 0.25 mol weighs 21 g.

Solution:
M = 21/0.25 = 84 g/mol
Answer: 84 g/mol

27. [NEET 2014]
Empirical formula of a compound with 52.2% C, 13% H, and 34.8% O?

Solution:
C: 52.2/12 ≈ 4.35, H: 13/1 = 13, O: 34.8/16 ≈ 2.175
Dividing by 2.175: C2, H6, O1 → C2H6O
Answer: C2H6O

28. [NEET 2015]
Which of the following has maximum number of atoms: 1g H2, 1g O2, 1g CH4, 1g He?

Solution:
1g H2 = 0.5 mol = 1 mol atoms → 6.022×10²³ atoms
Answer: H2

29. [NEET 2016]
Which of the following contains max number of molecules: 2g H2, 44g CO2, 16g O2, 18g H2O?

Solution:
Mol:
H2: 2/2 = 1
CO2: 44/44 = 1
O2: 16/32 = 0.5
H2O: 18/18 = 1
→ Tie among H2, CO2, H2O (all have 1 mol = 6.022×10²³)
Answer: All three (equal molecules)

30. [NEET 2017]
Volume of 4.4g CO2 at STP?

Solution:
M = 44 → mol = 4.4 / 44 = 0.1 mol → V = 0.1 × 22.4 = 2.24 L
Answer: 2.24 L

31. [NEET 2018]
Mole fraction of solute when 5.3 mol solute in 94.7 mol solvent?

Solution:
= 5.3 / (5.3 + 94.7) = 0.053
Answer: 0.053

32. [NEET 2019]
What mass of oxygen is required to burn 12 g CH4 completely?

Solution:
CH4 + 2O2 → CO2 + 2H2O
Moles CH4 = 12/16 = 0.75
→ O2 required = 1.5 mol = 1.5×32 = 48 g
Answer: 48 g

33. [NEET 2020]
How many atoms in 1 mol of H2SO4?

Solution:
H2SO4 → 7 atoms → 7×6.022×10²³ = 4.215×10²⁴
Answer: 4.215×10²⁴

34. [NEET 2021]
0.5 mol Al reacts with HCl. How many mol of H2 gas formed?

Solution:
2Al + 6HCl → 3H2
0.5 mol Al → 0.75 mol H2
Answer: 0.75 mol

35. [NEET 2022]
How many moles of Na+ in 0.2 mol Na2SO4?

Solution:
Na2SO4 → 2Na⁺ → 0.2×2 = 0.4 mol
Answer: 0.4 mol

36. [NEET 2023]
Calculate empirical formula of compound: 80% C, 20% H by mass.

Solution:
C = 80/12 ≈ 6.67, H = 20/1 = 20
Divide by 6.67: C1H3
Answer: CH3

37. [NEET 2024]
1.5 mol of which gas at STP occupies maximum volume?
Options: O2, H2, N2, Cl2

Solution:
All gases at STP: 1.5 mol × 22.4 = 33.6 L → All same
Answer: All same (33.6 L)

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✅ That’s a full 38-year collection of Mole Concept PYQs with step-by-step solutions!
Perfect for your NEET prep – keep practicing! ✅ 

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