There are several different models that represent compounds. One type of model is shown. 3 C's connected in a line by 2 black lines. The first and third C's each have 3 H's connected to them by a single black line each. The middle C has 2 H's connected to it by a single black line each.
What type of model is shown?

a structural formula
a chemical formula
a space-filling model
a ball-and-stick model

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.

nuclear fission produces elements that are heavier than helium.

the elements that are used in nuclear fission and their products are much heavier than helium.