<u>Answer:</u> The mass of iron (II) oxide that contains a million iron atoms is 
<u>Explanation:</u>
We are given:
Number of iron atoms = A million = 
The chemical formula of the given compound is 
It is formed by the combination of 2 iron atoms and 3 oxygen atoms.
According to mole concept:
1 mole of a compound contains
number of particles
1 mole of iron (II) oxide will contain =
number of iron atoms
We know that:
Molar mass of iron (II) oxide = 159.7 g/mol
Applying unitary method:
For
number of iron atoms, the mass of iron (II) oxide is 159.7 g
So, for
number of iron atoms, the mass of iron (II) oxide will be 
Hence, the mass of iron (II) oxide that contains a million iron atoms is 
<span>) 8% solution means 8g/100 ml. So 500 ml= 40g. </span>
Answer:
NH3 , SO3 , BF3
Explanation:
trigonal planar = AB3 ------------> Coordination number = 3
for example = NH3 , SO3 , BF3
all of them are trigonal planar