Question

The variable coefficients d, e, f and g are considered for balancing the chemical equation. Relationships between these variable are constructed by balancing the atoms of each element on either side of the reaction. Which of the following are correct?

(Note: Coefficients should be natural numbers.)

(i) 2d= f, d = 3g and e= f + 2g

(ii) 2d = f, 3d = g and 2e = 2f + g

(iii) d = f2, 2d = g and e = 2f + 2g

(iv)d = 1, e = 3.5, f = 4 and g = 6

(v) d = 2, e = 7, f = 4 and g = 6

(vi) d = 2, e = 7, f = 3 and g = 4

• A. (ii), (iv)
• B. (ii), (v)
• C. (vi), (i)
• D. (v), (iii)

Answer 1

The correct option is B

(ii), (v)

Select element Carbon (C) there are '2d' number of atoms of it on reactant side and 'f' number of electrons on product side and these should be equal.

=> 2d = f

$$\begin{array}{cccc}Element& Numberofatomsonreactantside& Numberofelementsonproductside& Equationformed\\ Carbon& 2d& f& 2d=f\\ Hydrogen& 6d& 2g& 3d=g\\ Oxygen& 2e& 2f+g& 2e=2f+g\end{array}$$

So we get the equation (from the table),

$2d=f,3d=gand2e=2f+g$.

$Letd=1$

Solving equations, we get,

$f=2$

$g=3$

$e=3.5$

We got e = 3.5, but Coefficients of the chemical equation can't be fractions or decimals.

So multiply all coefficients by 2, the equation still remains the same. We get the final values of d, f, g and e respectively as 2, 7, 4 and 6.

The final balanced equation becomes