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JEE Main202621 January 2026Morning ShiftChemistrySome Basic Concepts of ChemistryActual

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 :

Options

  1. AC ₂ H ₂
  2. BC ₂ H ₄
  3. CC ₂ H ₆
  4. DC ₄ H ₁₀

Correct answer

A. C ₂ H ₂

Step-by-step solution

KOH absorbs CO₂ . Volume of CO₂ produced = 224 - 64 = 160 mL Unreacted O₂ = 64 mL, so O₂ consumed = 264 - 64 = 200 mL For hydrocarbon C_xH_y : CO₂ Hydrocarbon = 160 80 = 2 x = 2 O₂ consumed per mole = x + y 4 = 200 80 = 2.5 2 + y 4 = 2.5 y = 2 Hydrocarbon is C₂H₂

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