Answer:
Formula of oxide is 
Explanation:
The given compound consists of Fe and O.
So, mass of oxygen in sample = (mass of sample) - (mass of Fe in sample)
= (6.285 g ) - (4.396 g)
= 1.889 g
Molar mass of O = 16 g/mol and molar mass of Fe = 55.845 g/mol
So, ratio of number of moles of Fe and O (Fe : O)
= 
= 0.0787 : 0.118
= 
= 1 : 1.5
= 2 : 3
So, formula of oxide is 
Answer:
The sum of the number of protons and neutrons in an atom is called the mass number.
Explanation:
Carbon-12 has 12 protons and 12 neutrons. 12+12=24 , so the mass number of C-12 is 24..
Hope it helps..