An element is a pure substance made up of only one kind of atom. An element is composed of atoms in which it is composed of neutrons and protons. The nucleus is surrounded by electrons. The answer to this problem is A. element
5.167g of calcium chloride is dissolved in 101.0mL of water in a calorimeter whose calorimeter constant is 15.3J/°C. The temperature rises from 18.4°C to 27.2 ...
This is percent composition
The formula for that is
(Mass of part/total mass) x 100
What’s the total molar mass of CO2?
12.01 +16(2) = 44.01 g/mol
What is the molar mass of Carbon?
Since there is only one carbon it is 12.01 g/mol
(12.01/44.01) x 100 = 27.29%
A is correct just compare answers with yahoo