Cracking saturated hydrocarbons yields H₂ and smaller alkanes

Steps:

• Recognize cracking as thermal decomposition of large alkanes into smaller molecules.
• Note typical products include hydrogen (H₂) and saturated hydrocarbons like C₄H₁₀ (butane).
• Eliminate options with H₂O, as water forms in combustion, not cracking.
• Select the pair matching H₂ and a valid smaller alkane.

Why A is correct:

• Cracking follows the general reaction for alkanes, producing H₂ and smaller saturated hydrocarbons, such as CₙH₂ₙ₊₂ → smaller CₘH₂ₘ₊₂ + H₂.

Why the others are wrong:

• B: C₃H₈ (propane) is possible, but context specifies C₄H₁₀ as the matching smaller alkane product.
• C: H₂O is not a cracking product; it requires oxygen, absent in cracking.
• D: H₂O invalidates the pair, as cracking does not generate water.

Final answer: A