Ans: D) 6
A reaction is said to be balanced when the number of atoms (of one type) is the same in both the reactants and the product side of the equation.
The given reaction is:
BF3 + Li2SO3 → B2(SO3)3 + LiF
Reactants Products
B = 1 B = 2
F = 3 F = 1
Li = 2 Li = 1
S = 1 S = 3
O = 3 O = 9
From the above atoms tally, it is clear that the B, F, Li, S and O atoms are unbalanced.
In order to balance it, multiply BF3 by 2, Li2SO3 by 3 and LiF by 6. The balanced equation is:
2BF3 + 3Li2SO3 → B2(SO3)3 +6 LiF
Therefore, coefficient of LiF is 6