Which equation illustrates conservation of mass? O 1 H2 + 1 O2 + 2 H2O
O 1 H2 + 1 2 + 1 H2O
O 1 H2 + 1 Cl2 +1HCI
O 1 H2 + 1 Cl2 + 2HCI

1H₂  +  1Cl₂  →   2HCl

Explanation:

The reaction that illustrates the law of conservation of mass is shown below:  

         1H₂  +  1Cl₂  →   2HCl

According to the law of conservation of mass "in a chemical reaction, matter is neither created nor destroy but atoms are rearranged".

Therefore, we are expected to the end a reaction with the amount of substance we start with.

 Element                                H                                    Cl

Reactants                               2                                      2

Products                                 2                                      2

We see that number of atoms on both sides are the same.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.