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Which hydrocarbon pair below have identical mass percentage of C?

What is the coefficient of O2 when the following equation is completed and balanced? C4H8O2 + O2 → __________

Propane (C3H8) reacts with oxygen in the air to produce carbon dioxide and water. In a particular experiment, 38.0 grams of carbon dioxide are produced from the reaction of 22.05 grams of propane with excess oxygen. What is the % yield in this reaction?

The electron configuration of the phosphide ion (P3-) is __________.

When the following equation is balanced, the coefficient of Al is __________. Al (s) + H2O (l) → Al(OH)3 (s) + H2 (g)

The ground-state electron configuration of __________ is [Ar]4s13d5.

The formula weight of lead (II) carbonate (PbCO3) is __________ amu.

A __________ covalent bond between the same two atoms is the longest.

Given the following reactions: 2S (s) + 3O2 (g) → 2SO3 (g) ΔH = -790 kJ S (s) + O2 (g) → SO2 (g) ΔH = -297 kJ the enthalpy of the reaction in which sulfur dioxide is oxidized to sulfur trioxide 2SO2 (g) + O2 (g) → 2SO3 (g)is __________ kJ.