Question

Which of the following chemical equations is correctly balanced?

Answer 1

Option B and C both are balanced.

A chemical reaction is said to be balanced if all the constituent on the left side of the reaction arrow are equal to right side.

(A) The chemical reaction is as follows:

$H_{2}+O_{2}\rightarrow H_{2}O$

There are 2 hydrogen atoms and 2 oxygen atoms on left side of the reaction arrow and 2 hydrogen and 1 oxygen on right hand side thus, number of oxygen atoms are not balanced.

Therefore, the above chemical reaction is not balanced.

(B) The chemical reaction is as follows:

$2C_{2}H_{4}O+5O_{2}\rightarrow 4CO_{2}+4H_{2}O$

There are 4 carbon atoms, 8 hydrogen atoms and 12 oxygen atoms on both side of the reaction arrow thus, the chemical reaction is balanced.

(C) The chemical reaction is as follows:

$K_{2}S+I_{2}\rightarrow 2KI+S$

There are 2 potassium atoms, 1 sulfur atom and 2 iodine atoms on both side of the reaction arrow thus, it is a balanced chemical reaction.

(D) The  chemical reaction is as follows:

$CaCO_{3}+2HCl\rightarrow CaCl_{2}+2CO_{2}+H_{2}O$

There is 1 calcium atom, 1 carbon atom, 3 oxygen atoms, 2 hydrogen atoms and 2 chlorine atoms on left side of the reaction arrow and 1 calcium atom, 2 chlorine atoms, 2 carbon atoms, 5 oxygen atoms and 2 hydrogen atoms on right hand side of the reaction arrow. Thus, number of carbon and oxygen atoms are not balanced in the chemical reaction.

Answer 2

The correct answer is B.