What is best classified as a physical change?

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned

The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.

Which diagram shows the correct way to represent an ionic compound of magnesium oxide?