JEE Main · 2026 · 05 Apr 2026 · Shift 1 · Some Basic Concepts of Chemistry

80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is:

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 $\mathrm{g}{\mathrm{mol}}^{-1}$ of $\mathrm{Ca}-40,\mathrm{Cl}-35.5,\mathrm{H}-1$]

In the reaction,
$2\mathrm{Al}(\mathrm{s})+6\mathrm{HCl}(\mathrm{aq})\to 2{\mathrm{Al}}^{3+}(\mathrm{aq})+6{\mathrm{Cl}}^{-}(\mathrm{aq})+3{\mathrm{H}}_2(\mathrm{g})$

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 $\mathrm{g}{\mathrm{mol}}^{-1}$: O=16, Mg=24, P=31)

At $\mathrm{T}(\mathrm{K}),100\mathrm{g}$ of $98\%{\mathrm{H}}_2{\mathrm{SO}}_4(\mathrm{w}/\mathrm{w})$ aqueous solution is mixed with 100 g of $49\%{\mathrm{H}}_2{\mathrm{SO}}_4(\mathrm{w}/\mathrm{w})$ aqueous solution. What is the mole fraction of …

$\mathrm{A}+2\mathrm{B}⟶{\mathrm{AB}}_2$

36.0 g of 'A' (Molar mass : $60\mathrm{g}{\mathrm{mol}}^{-1}$ ) and 56.0 g of ' B ' (Molar mass : $80\mathrm{g}{\mathrm{mol}}^{-1}$ ) are allowed to react. Which of the following statements are correct?
(A) ' A …