Which statement best describes the role that gravity played in the formation of our solar system? a. gravity allowed the nebula to expand and move outward. b. gravity caused the nebula to cool enough for planets to form. c. gravity removed excess gas and dust from the cores of the planets. d. gravity pulled particles of dust and gas together to form planets.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

you need to stop taking that class