Fasss

what did you notice about the way the soil particles sank in the water? how was it different from the way the soil and sand particles sank?

what does the soil look like in the "soil" bottle? how is it different from the soil in the "soil and sand" bottle?

it's c (engineer's do their work with mechanical stuff not on any living being)

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