Chris is researching the claim that people with longer legs can run faster than people with shorter legs. Which of the following is a reliable source of information for his research? A.
interviews with tall and short friends
B.
newspaper editorials
C.
scientific journals
D.
all of these

the correct answer is:

a. formation of precipitation

idk what is it? is this a question that you know the answer or u dont

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