Please help me. The diagram below shows the structures of a plant cell.

What is structure 1, and how does it help sustain life?

A.
Structure 1 is the cell wall, which provides structural support for the cell.
B.
Structure 1 is a chloroplast, which is the site of photosynthesis.
C.
Structure 1 is a vacuole, which temporarily stores wastes.
D.
Structure 1 is the nucleus, which is the control center of the cell.

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