The chemical reaction in which number of atoms of each element present in the reactant side is equal to the number of atoms of that element in product side, such reactions are said to be a balanced chemical reaction.
The chemical symbol for sodium is
.
The chemical symbol for fluorine gas is
.
The chemical symbol for sodium fluoride is 
The sodium fluoride is prepared from the reaction between sodium metal and fluorine gas can be written as:

The above reaction is not balanced as the number of fluorine atoms are not same on reactant and product side. So, in order to balance the reaction we will multiply
with 2 on reactant side and
with 2 on product side. Thus, the balanced reaction will be:

Thus, the balanced chemical equation is
.
Answer:
See explanation
Explanation:
The law of conservation of mass states that mass can neither be created nor destroyed. This implies that in a chemical reaction, we can only have the same number of atoms of each element on both sides of the reaction equation.
If we write 4Fe2S3 it means that we have;
4 * 2 = 8 atoms of Fe
4 * 3 = 12 atoms of S
8 + 12 = 20 atoms in all
Answer:
halogen
Explanation:
It belongs to Group 17 on the periodic table, which is a halogen
Moving from Ethanol through Propanol to Butanol the physical properties like boiling points, surface tension and viscosity increases because of the increases in intermolecular interactions between the molecules of given compounds.
Explanation:
Ethanol, propanol and butanol all have hydroxyl groups in common, means all have hydrogen bond intractions between their molecules. So, taking the hydrogen bonding interaction constant we are left with only the difference in the number of carbon atoms.
Butanol has the greatest physical properties than other two because it has four carbon atom chain. So, as we know the London Dispersion forces or Van der Waal forces increases with increase in molecular size and chain length of hydrocarbon.
Therefore, the strength of London forces is greater in butanol than other two while ethanol has the smallest chain comparatively hence, lowest physical properties.
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