a study was done to find if different tire treads affect the breaking distance of a car what is the independent variable the dependent variable and the constant

Independent variable: Different tyre treads

Dependent variable: Breaking distance

Constant: Same car

Explanation:

In an experiment, an independent variable is that variable which the experimenter controls or manipulates to effect an outcome. In this experiment, the tyre treads are changed to see if it would affect the breaking distance, hence, the DIFFERENT TYRE TREADS is the independent variable.

On the other hand, a dependent variable is the variable that responds to the manipulation of the independent variable. In other words, it is the outcome of the experiment. In this experiment, the BREAKING DISTANCE is the responding or dependent variable.

Constant or controlled variable is that variable that is kept constant or unchanged throughout the course of the experiment. The constant, if changed, will influence the result of the experiment. The constant in this experiment is the CAR since the same car (unchanged) was used for the experiment.

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