Question

multiple choice
identify the choice that best completes the statement or answers the question.

1. in a line graph, what is plotted on the x - axis?

a) dependent variable
c) controlled variable
b) exponential variable
d) independent variable
chemical reactions do not happen instantaneously. some are fast (lighting a stick of dynamite), some are
slow (a car rusting). the graph below shows an example of a chemical reaction and how much of that
reaction has been completed in a certain amount of time. use the graph to answer the questions
below...

1. what is occurring to the rate of reaction as time progresses?

a) slowing down, then speeding up
c) its slowing down
b) increasing at constant rate
d) its speeding up

1. what is the dependent variable?

a) density
c) reaction rate
b) time
d) % completed

1. how much time will it take for the reaction to be 40% complete?

a) 12.3 sec
c) 12.6 sec
b) 12 sec
not an option

Explanation:

Step1: Analyze question 1

In a line graph, the independent variable is plotted on the \(x -\)axis.

Step2: Analyze question 2

Looking at the graph, as time (\(x -\)axis) progresses, the slope of the line (which represents the rate of change of \(\%\) of reaction completed with respect to time) is increasing. So the rate of reaction is speeding up.

Step3: Analyze question 3

The dependent variable depends on the independent variable. Here, \(\%\) of reaction completed (\(y -\)axis) depends on time (\(x -\)axis).

Step4: Analyze question 4

Looking at the graph, when \(\%\) of reaction completed is \(40\), the corresponding time on the \(x -\)axis is \(12\) seconds.

Answer:

1. d) independent variable
2. d) it's speeding up
3. d) \(\%\) completed
4. b) \(12\) sec