Explanation:
According to the law of conservation of mass, mass can neither be created nor destroyed but it can simply be transformed from one form to another.
For example, 
Mass of Na = 23 g/mol
Mass of Cl = 35.5 g/mol
Sum of mass of reactants = mass of Na + mass of Cl
= 23 + 35.5 g/mol
= 58.5 g/mol
Mass of product formed is as follows.
Mass of NaCl = mass of Na + mass of Cl
= (23 g/mol + 35.5) g/mol
= 58.5 g/mol
As mass reacted is equal to the amount of mass formed. This shows that mass is conserved.
As a result, law of conservation of mass is obeyed.
2.0 L in mL :
2.0 x 1000 => 2000 mL
1.26 kg in g :
1.26 x 1000 => 1260 g
D = mass / volume
D = 1260 / 2000
D = 0.63 g/mL
hope this helps!
The human body has 23 pairs of chromosomes or 46 chromosomes in total that make up our traits and DNA
Gold and helium are examples of elements