All of the following statements about the nitrogen cycle are incorrect, except which?
assimilation is the process by which plants absorb and use nitrates.
nitrogen fixation is prevented by the presence of ammonium in the soil.
denitrification occurs when there’s a shortfall of available nitrogen in the soil.
the nitrogen cycle works best when bacteria are eliminated from the process.

It’s not number 3 or 4, Denitrification occurs when there’s a shortfall of available nitrogen in the soil. Or The nitrogen cycle works best when bacteria are eliminated from the process. I think its Number 1 or Assimilation is the process by which plants absorb and use nitrates.

Explanation:

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