Question

1. choose the best answer.

what is likely a reactant in a combustion reaction?
○ heat
○ c₂h₁₀
○ ca⁺
○ light

1. choose the best answer.

what is always produced during a combustion reaction?
○ hydrogen gas
○ salts
○ metals
○ water

Explanation:

Question 8

Combustion reactions involve a fuel (usually a hydrocarbon) reacting with oxygen. Heat and light are products, not reactants. \( \text{Ca}^+ \) is an ion, not typical in combustion. \( \text{C}_2\text{H}_{10} \) (a hydrocarbon, though likely a typo for \( \text{C}_2\text{H}_6 \) or similar) is a fuel/reactant.

Combustion of hydrocarbons (or substances with H and C) produces \( \text{CO}_2 \) and \( \text{H}_2\text{O} \). Hydrogen gas, salts, and metals are not always products. Water is always produced when there's hydrogen in the reactant.

Answer:

B. \( \text{C}_2\text{H}_{10} \) (assuming the options are labeled as A: heat, B: \( \text{C}_2\text{H}_{10} \), C: \( \text{Ca}^+ \), D: light)

Question 9