Its a covalent bond for this q
Look at the periodic table to find the charge on atoms.
Magnesium is +2 and Nitrogen is -3. Since there are two nitrogen charge 2*-3 = -6 there needs to be 3 Mg then (3*2+ = 6+) to pair with the two nitrogen.
3 Mg(+2) + 2 N(-3) = Mg3N2
Acetic Acid has two C atoms, four H atoms, and two O atoms, so the molecular formula is C2H4O2.
I don’t think you can get it for
Answer : The mass defect required to release energy is 6111.111 kg
Explanation :
To calculate the mass defect for given energy released, we use Einstein's equation:

E = Energy released = 
= mass change = ?
c = speed of light = 
Now put all the given values in above equation, we get:


Therefore, the mass defect required to release energy is 6111.111 kg