A calorie is equal to 4.18 joules and 1000 calories is equal to 1 Calorie. A Calorie with a capital "c" is what food is measured in.
Okay... what are the following
Among the choices, the polyatomic ion is only the third choice, NH4+ where it is composed of nitrogen one atom of nitrogen and 4 atoms of hydrogen. Choice 2 is a monoatomic atom being composed only of calcium. Then, the first and fourth choices are not ions because they are not charged.
