Justine just added a new rock to her collection. To learn what type of rock it is, Justine wants to calculate the rock's density She first weighs the rock and finds that its mass is 43 g. To find its volume, she puts it in a container filled with 80 mL of water. When the rock is added, the water level changes to 100 mL, which is equal to 100 cm? The diagram below shows the water level change 100 mL 80 mL → + What is the density of the rock? A. 6.14g/cm

B 2.15g/cm

C 0.43

D 0.24​

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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