As Fire needs oxygen to burn, Carbon Dioxide Covers the fire like an blanket and cuts the contact of fire to the oxygen present in the air, So Fire stops burning.That is why Carbon Dioxide is Considere as the best Fire Extinguisher.
Answer: 39 electrons
Explanation: Subtract 79 by 40 to get the atomic number (amount of protons) which is 39. The number of electrons must be the same as the number of protons if it's not an ionic compound so the amount of electrons is the same amount of protons.
The answer to your question is : no.of moles of Si = 43/atomic mass of Si = 43/28.1 = 1.53
according to reaction 3 moles of Si gives 1 mole of Si3N4
so 1.53 mole of Si will give 1.53/3 = 0.51 mole of Si3N4
molar mass of Si3N4 = 140.28 g/mole
it means that 1 mole of Si3N4 = 140.28 g
so 0.51 mole of Si3N4 = 0.51 X 140.28 = 71.543 g