I think the answer is C. An element or compound that cannot be physically separated. Sorry if im wrong.
a. 48.6 is magnesium and 32.0 is oxygen
b. 80.6
c. also 80.6
d. yes, because the product has equal mass to the reactants
The semi will have the hardest time changing direction because of its mass. The more mass there is, the more effort it takes to accelerate and decelerate as well as change direction.
