Hydrogen & s-Block · JEE Main previous year questions

2026 6 questions

1. Q702026 · 5 Apr 2026 · Shift 1

   Given below are two statements: Statement I: Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis. Statement II: Phenolphthalein is a weak base, therefore it dissociates in acidic medium. In the light of the above statements, choose the correct answer from the options given below

   1. A.Both Statement I and Statement II are ture
   2. B.Both Statement I and Statement II are false
   3. C.Statement I is true but Statement II is false
   4. D.Statement I is false but Statement II is true
   Show answer

   Answer: B

2. Q612026 · 4 Apr 2026 · Shift 1

   Correct statements from the following are A. Potassium dichromate is an oxidising agent and it oxidises $\mathrm{FeS}{\mathrm{O}}_4$ to $\mathrm{F}{\mathrm{e}}_2(\mathrm{S}{\mathrm{O}}_4{)}_3$ in acidic medium. B. Sodium dichromate can be used as primary standard in volumetric estimation. C. $\mathrm{Cr}{\mathrm{O}}_4^{2-}$ and $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}$ are interconvertible in aqueous solution by varying the $\mathrm{pH}$ of the solution. D. $\mathrm{Cr}\text{-}\mathrm{O}\text{-}\mathrm{Cr}$ bond angle in $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}$ is $126^{\circ }$. Choose the correct answer from the options given below:

   1. A.A, B and C Only
   2. B.A, C and D Only
   3. C.A and C Only
   4. D.B and D Only
   Show answer

   Answer: B

3. Q712026 · 2 Apr 2026 · Shift 2· Numerical answer

   The surface of sodium metal is irradiated with radiation of wavelength $x\text{ nm}$. The kinetic energy of ejected electrons is $2.8\times 10^{-20}\text{ J}$. The work function of sodium is $2.3\text{ eV}$. The value of $x$ is ________ $\times 10^2\text{ nm}$. (Nearest integer) (Given : $h=6.6\times 10^{-34}\text{ J s}$ ; $1\text{ eV}=1.6\times 10^{-19}\text{ J}$; $c=3.0\times 10^8{\text{ m s}}^{-1}$)

   Show answer

   Answer: 5

4. Q732026 · 23 Jan 2026 · Shift 2· Numerical answer

   200 cc of $x\times 10^{-3}\text{M}$ potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here $x=$ _____.

   Show answer

   Answer: 375

5. Q642026 · 21 Jan 2026 · Shift 1

   14.0 g of calcium metal is allowed to react with excess HCl at 1.0 atm pressure and 273 K . Which of the following statements is incorrect? [Given : Molar mass in $\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ of $\mathrm{Ca}-40,\mathrm{Cl}-35.5,\mathrm{H}-1$ ]

   1. A.The limiting reagent is calcium metal.
   2. B.33.3 g of $\mathrm{CaC}{\mathrm{l}}_2$ is produced.
   3. C.7.84 L of ${\mathrm{H}}_2$ gas is evolved.
   4. D.0.35 mol of ${\mathrm{H}}_2$ gas is evolved.
   Show answer

   Answer: B

6. Q632026 · 21 Jan 2026 · Shift 2

   By usual analysis, 1.00 g of compound (X) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : (nearest integer) (Given, molar mass in g $\mathrm{mo}{\mathrm{l}}^{-1}$: O = 16, Mg = 24, P = 31)

   1. A.40
   2. B.30
   3. C.20
   4. D.50
   Show answer

   Answer: D