Respuesta :

it is halved and the sign is changed by  the chemical reaction

Answer: The correct answer is Option 1.

Explanation:

We are given two intermediate equations and a final net equation for the formation of calcium carbonate. To form a net equation, we have to apply some operations on the second equation.

Two intermediate equations given are:

[tex]Ca(s)+CO_2(g)+\frac{1}{2}O_2(g)\rightarrow CaCO_3(s)[/tex]      [tex]\Delta H_1=-812.8kJ[/tex]

[tex]2Ca(s)+O_2(g)\rightarrow 2CaO(s)[/tex]       [tex]\Delta H_2=-1269.8kJ[/tex]

To get the final equation, we will half the second equation and reverse the equation, we get:

Equation 1:       [tex]Ca(s)+CO_2(g)+\frac{1}{2}O_2(g)\rightarrow CaCO_3(s)[/tex]

Equation 2:       [tex]CaO(s)\rightarrow Ca(s)+\frac{1}{2}O_2(g)[/tex]

Net Equation:    [tex]CaO(s)+CO_2(g)\rightarrow CaCO_3(s)[/tex]

Hence, the correct answer is Option 1.