Hydrogen JEE Main previous year questions with solutions

5 solved JEE Main questions on Hydrogen, free to read — no sign-in needed. The full chapter has 95 questions; sign in to attempt the remaining 90 in the exam simulator.

1. Q1JEE Main 2026 (02 Apr, Shift 1)
   The mass of iron converted into $Fe_3O_4$ by the action of $18$ g of steam is : (Given : Molar mass of H, O and Fe are $1$, $16$ and $56$ g mol$^{-1}$ respectively) Assume iron is present in excess :
   1. A.$2.1$ g
   2. B.$4.2$ g
   3. C.$21$ g
   4. D.$42$ g
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   Answer: (D)

   The balanced chemical equation for the reaction of iron with steam is: $3Fe + 4H_2O \rightarrow Fe_3O_4 + 4H_2$ Molar mass of $H_2O = 2 \times 1 + 16 = 18 \text{ g mol}^{-1}$ Number of moles of steam ($H_2O$) given = $\dfrac{18}{18} = 1 \text{ mol}$ From the balanced equation, $4 \text{ moles}$ of $H_2O$ react with $3 \text{ moles}$ of $Fe$. Therefore, $1 \text{ mole}$ of $H_2O$ will react with $\dfrac{3}{4} \text{ moles}$ of $Fe$. Mass of iron reacted = Moles of $Fe \times$ Molar mass of $Fe$ Mass of iron = $\dfrac{3}{4} \times 56 = 3 \times 14 = 42 \text{ g}$ Answer: $42$ g
2. Q2JEE Main 2023 (13 Apr, Shift 2)
   Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Isotopes of hydrogen have almost same chemical properties, but difference in their rates of reactions. Reason R: Isotopes of hydrogen have different enthalpy of bond dissociation. In the light of the above statements, choose the most appropriate answer from the options given below:
   1. A.Both A and R are correct but R is NOT the correct explanation of A
   2. B.Both A and R are correct and R is the correct explanation of A
   3. C.A is not correct but R is correct
   4. D.A is correct but R is not correct
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   Answer: (B)

   While isotopes of an element have the same electronic configuration, their chemical properties can differ slightly due to differences in their atomic mass. Isotopes of an element have the same number of protons but varying numbers of neutrons, which affects the overall mass of the atom. The only difference is in their rates of reactions, mainly due to their different enthalpy of bond dissociation.
3. Q3JEE Main 2023 (13 Apr, Shift 1)
   Given below are two statements: Statement I: Permutit process is more efficient compared to the synthetic resin method for the softening of water. Statement II: Synthetic resin method results in the formation of soluble sodium salts. In the light of the above statements, choose the most appropriate answer from the options given below:
   1. A.Both the statements $I$ and $II$ are incorrect
   2. B.Statement $I$ is incorrect but statement $II$ is correct
   3. C.Both the statements $I$ and $II$ are correct
   4. D.Statement $I$ is correct but statement $II$ is incorrect
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   Answer: (A)

   The difference between the zeolite and ion exchange process is that the zeolite process uses the mineral zeolite as the exchanging resin for cations in the hard water whereas the ion exchange process include several different resins for the ion exchange. Synthetic resins method is more efficient as it can exchange both cations and anions.
4. Q4JEE Main 2023 (11 Apr, Shift 2)
   Which hydride among the following is less stable?
   1. A.${BeH}_{2}$
   2. B.$HF$
   3. C.${NH}_{3}$
   4. D.$LiH$
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   Answer: (A)

   ${BeH}_{2}$ is indeed considered to be less stable compared to other hydrides among the given due to its significant covalent character and electron deficiency. Beryllium, being a small and highly charged cation, attracts the electrons in the $Be-H$ bonds more strongly, resulting in a greater degree of electron sharing between beryllium and hydrogen. This covalent character is in contrast to other alkaline earth metal hydrides, which tend to have more ionic character.
5. Q5JEE Main 2023 (10 Apr, Shift 2)
   Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Physical properties of isotopes of hydrogen are different. Reason R : Mass difference between isotopes of hydrogen is very large. In the light of the above statements, choose the correct answer from the options given below:
   1. A.Both A and R are true and R is the correct explanation of A
   2. B.A is false but R is true
   3. C.A is true but R is false
   4. D.Both A and R are true but R is NOT the correct explanation of A
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   Answer: (A)

   The isotopes of hydrogen are protium, deuterium, and tritium, which have different physical properties. For example, deuterium has a higher boiling point and a lower vapor pressure than protium, while tritium is radioactive and has a much shorter half-life than the other two isotopes. The mass difference between the isotopes of hydrogen is indeed significant, with protium having a mass of $1$ atomic mass unit (amu), deuterium having a mass of $2$ amu, and tritium having a mass of $3$ amu. So Both A and R are true and R is the correct explanation of A.