Answer:
1)Na2O
let the valency of Na is x
2(x)+(2)=0
2x+2=0
2x=-2
x=-1
2)ZnO
let the valency of Zn is x
x+2=0
x=-2
3)Al2O3
let the valency of Al is x
2(x)+3(2)=0
2x+6=0
2x=-6
x=-3
4)MgO
let the valency of Mg is x
x+2=0
x=-2
Answer: There are 
formula units
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
1 mole of 
contains = formula units
Thus 0.38 moles of contains = 
formula units
Thus there are formula units
B. Distillation
Distilling is when you boil a substance and collect the vapors.
Carbonic acid undergoes decomposition reaction. Decomposition reaction starts with one reactant and forms two or more products: AB⇒A+B. In this reaction, H2CO3 ⇒H2O + CO2.
