Answer:
Explanation:
To solve this problem, we must understand the relationship between mass of a substance and the number of atoms.
Atoms are the smallest indivisible particles of any matter. A substance can be made up of several number of atoms in their space.
The mass of any substance is a function of the amount of atoms its contains.
The mass of a substance is related in chemistry to the amount of atoms its contains using the parameter called the number of moles.
A mole is the amount of substance that contains the Avogadro's number of particles. This number is 6.02 x 10²³ particles. The particles here can be protons, neutrons, electrons, atoms e.t.c.
Now,
Number of moles = 
Molar mass of copper = 63.6g/mole
Number of moles = 
= 0.03mole
Since 1 mole of a substance contains 6.02 x 10²³atoms
0.03 mole of copper will contain 0.03 x 6.02 x 10²³atoms
= 1.89 x 10²² atoms
He needs to add 1.89 x 10²² atoms to make 2g of the sample.
1)The branch of science concerned with the substances of which matter is composed and it is a study of matter.
2)It helps you understand the world around you,chemistry helps you to understand product labels and etc.
3)You find chemistry in daily life in the foods you eat,the air you breathe,cleaning chemicals and etc.
4) Physical,Analytical, Biochemistry,Organic and inorganic chemistry.
Since particles are closer together, solids conduct heat better than liquids or gases. Conduction moves heat through a material. It keeps a fire going by spreading the heat through solid material. Radiation is a method of heat transfer that does not require particles to carry the heat energy.
The volume of a gas is the same as its CONTAINER.
Gases generally has no shape and no definite volume. When a gas is placed in a container, the gas usually takes the shape and the volume of the container, that is, the gas fills up all the available spaces in the container. Thus, the volume of a gas will always be the same as its container. This is in contrast with solids, which have definite shape and volume and liquids, which have definite volume but no fixed shape.
C = 4 mol/l
v = 0.5 l
n(NaCl)=cv
n(NaCl) = 4 mol/l · 0.5 l = 2 mol
2 moles of NaCl must be dissolved
