Mercury is environmental pollutant that is produced by the burning of fossil fuels and can be toxic to wildlife and humans. what does this show about the impact of chemicals on the environmental?
a. the beneficial effects people get from chemicals may have unintended harmful effects on the environment.
b. people cannot control the negative effects of chemicals on the environment.
c. the harm chemicals could have on the environment outweighs the benefits that people get from the chemicals.
d. all chemicals that people introduce into the environment are harmful.

3 1/4 %

explanation:

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.

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