Question

first, select the model of a molecule composed of two carbon atoms and six hydrogen atoms.
(h: white, c: black)
options: ethane (model with two c and six h), ethyne (model with two c and two h), propene (model with three c)
next, select the chemical formula for the substance composed of these molecules.
options: c₂h₆, c₂h₄, c₂h₂

Explanation:

Part 1: Select the molecule model

The molecule has 2 C and 6 H atoms. Ethane ($\ce{C2H6}$) has 2 C and 6 H; ethyne has 2 C and 2 H, propene has 3 C. So the first model (ethane) matches.

A molecule with 2 C and 6 H has the formula $\ce{C2H6}$. $\ce{C2H4}$ has 2 C and 4 H, $\ce{C2H2}$ has 2 C and 2 H.

Answer:

The model labeled "ethane" (the first molecular model with two carbon atoms and six hydrogen atoms).

Part 2: Select the chemical formula