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Chemistry - Some Basic Concepts of Chemistry

Practise 28 WBJEE previous year questions on Some Basic Concepts of Chemistry, compiled from papers spanning 2009 to 2025. Each question is pulled directly from the actual exam paper it appeared in, so you're practising in the exact style and difficulty WBJEE tests.

Some Basic Concepts of Chemistry has been asked in 14 of the 18 years of WBJEE papers analysed (2009–2026), with 28 questions in all. 29% of them were easy, 46% moderate and 25% tough. Most of its questions came from 2022, with 4 questions that year. In the last three years (2024–2026) it had 1 question across 3 papers, about 0.3 per paper.

The chapter's 4 topics are not weighted equally: Mole concept (17 questions, 61%), Concentration terms (8 questions, 29%), and Quantitative measures in chemical equations (2 questions, 7%) have been asked the most. Mole concept has also led over the last five years, with 4 questions. Mole concept has produced the most tough questions (5).

  1. 1How many oxygen atoms are present in 0.36 g of a drop of water at STP?2025Mole concept
  2. 2Arrange the following in order of increasing mass I. 1 mole of \( {N}_2\) II. \(0.5 {~mole}^2\) of \( {O}_3\) III. \(3.011 10^{23} {molecule2023Mole concept
  3. 3\(63 {~g}\) of a compound (Mol. Wt. \(=126)\) was dissolved in \(500 {~g}\) distilled water. The density of the resultant solution as \(1.122023Concentration terms
  4. 4Avogadro's law is valid for2022Laws of chemical combination
  5. 5A metal (M) forms two oxides. The ratio (by weight) in the two oxides are and . The minimum value of atomic mass of is2022Mole concept
  6. 6of water has 25 drops. Let be the Avogadro number. What is the number of molecules present in 1 drop of water ? (Density of water )2022Mole concept
  7. 7Benzene burns in oxygen according to the above equation. What is the volume of oxygen (at STP) needed for complete combustion of 39 gram of 2022Quantitative measures in chemical equations
  8. 8The mole fraction of a solute in a binary solution is At , molarity of this solution is same as as its molality. Density of this solution at2021Concentration terms
  9. 9The mole fraction of ethanol in water is . Its molality is2020Concentration terms
  10. 10of is mixed with of . The amount of precipitated will be about2020Concentration terms
  11. 11Which of the following has the largest number of atoms?2020Mole concept
  12. 12What will be the mass of one atom of ?2020Mole concept
  13. 13In the crystalline solid of molar mass 250 g , the percentage of anhydrous salt is 64 by weight. The value of is2019Mole concept
  14. 14At S.T.P. the volume of of a gas is . The gas is2019Mole concept
  15. 15How many moles of electrons will weigh one kilogram?2018Mole concept
  16. 16A metal (specific heat 0.16 ) forms a metal chloride with chlorine present in it. The formula of the metal chloride will be2018Quantitative measures in chemical equations
  17. 17In a flask, the weight ratio of and at and 1 bar is The ratio of the number of molecules of and is2017Mole concept
  18. 18What will be the normality of the salt solution obtained by neutralising mL. (N) HCl with mL (N) , and finally adding distilled water2017Concentration terms
  19. 19The system that contains the maximum number of atoms is2014Mole concept
  20. 20The volume of ethyl alcohol (density ) that has to be added to prepare of ethyl alcohol solution in water is2014Mole concept
  21. 21Number of hydrogen ions present in 10 milionth part of of pure water at is2013Mole concept
  22. 22Equal weights of and are mixed in an empty container at . the fraction of the total pressure exerted by is2012Mole concept
  23. 23Identify the method by which can be prepared.2012Mole concept
  24. 24The weight of oxalic acid that will be required to prepare a solution is2012Mole concept
  25. 25The normality of 30 volume \( {H}_2 {O}_2\) is2011Concentration terms
  26. 26The molarity of a solution by dissolving of it in water is2010Concentration terms
  27. 27Which of the following will decrease the of a solution of ?2009Concentration terms
  28. 28An organic compound made of and contains nitrogen. Its molecular weight is :2009Mole concept

Frequently Asked Questions

1.How many questions are available for Some Basic Concepts of Chemistry?

This chapter includes 28 questions compiled from WBJEE papers spanning 2009 to 2025.

2.Are these questions only from WBJEE, or from other exams too?

These are WBJEE questions specifically for the Some Basic Concepts of Chemistry chapter. Questions from other exams like JEE Main or NTA Abhyas (JEE Main) are organised separately under their respective exam sections.

3.Is Some Basic Concepts of Chemistry an important chapter for WBJEE Chemistry?

Some Basic Concepts of Chemistry has appeared in 14 of the 18 years of WBJEE papers covered here, with 28 questions across 14 papers - about 2 per paper it appears in.

4.What is the difficulty level of Some Basic Concepts of Chemistry questions in WBJEE?

Of the 28 questions analysed for this chapter, 29% are easy, 46% moderate and 25% tough. 2022 had the most, with 4 questions.

5.Which topics in Some Basic Concepts of Chemistry should I focus on?

These topics have carried the most weightage in Some Basic Concepts of Chemistry:

  • Mole concept - 17 questions (61%)
  • Concentration terms - 8 questions (29%)
  • Quantitative measures in chemical equations - 2 questions (7%)
  • Mole concept has produced the most tough questions (5).
6.Is Some Basic Concepts of Chemistry's weightage in WBJEE going up or down?

Across all 14 papers analysed, Some Basic Concepts of Chemistry has averaged about 2.0 questions per paper. In the last three years (2024–2026), that average has fallen, at about 0.3 questions per paper. Use the year-wise numbers on this page for the exact trend before you decide how much time to give it.