Deck 7: Proportionality, Graphs, and Rates of Change

Question 1

The following graph is the standard curve for absorbance of an analyte.
In the laboratory,you are presented with a solution with an unknown concentration of the analyte.You measure the absorbance of the solution and determine it to be 0.40.Based on this standard curve,which of the following is the most accurate estimate of the analyte's concentration in the solution?

A) 0 mg/ml
B) 0.004 mg/ml
C) 0.007 mg/ml
D) 0.012 mg/ml

Answer 1

0.007 mg/ml

Question 2

Consider the following equation: y = 2x + 4
For every change of 1 in x,how much does the value of y change?

A) 0
B) 1
C) 2
D) 4

Answer 2

2

Question 3

The following equation represents the proportionality of two variables: y = -2x
If the value of x increases,which of the following is true regarding the value of y?

A) It will become independent of x.
B) It will decrease.
C) It will increase.
D) It will remain unchanged.

Answer 3

It will decrease.

Question 4

The equation "y = mx + b" describes a

A) curved line.
B) nonlinear constant.
C) standard curve.
D) straight line.

Question 5

Which of the following statements is true regarding the variables in an equation that produces a straight line with a negative slope?

A) The two variables move in opposite directions, and are proportional.
B) The two variables move in opposite directions, but are not proportional.
C) The two variables move in the same direction, and are proportional.
D) The two variables move in the same direction, but are not proportional.

Question 6

The slope of a straight line is best described as

A) the change in the value of x divided by the change in the value of y.
B) the dividend between the ordinate value and the inordinate value.
C) the ratio of the change in the dependent variable to the change in the independent variable.
D) the value of the proportionality constant divided by the value of x.

Question 7

Which of the following equations represents the proportionality of two variables,where one variable is always five times the value of the other?

A) 5y = 5x
B) 5y = x + 5
C) y = 5x
D) y = x + 5

Question 8

A scientist quantifies the product formed in a chemical reaction as a function of time and plots the data on a graph.The data generate a straight line.The slope of this line represents which of the following?

A) The speed of product formation by the chemical reaction
B) The energy expended by the chemical reaction to form the product
C) The rate of change in the amount of the product formed by the chemical reaction
D) Both A and C are correct.

Question 9

The following equation represents the proportionality of two variables: y = 4x
What is the proportionality constant of this equation?

A) 4
B) 4x
C) x
D) y

Question 10

The following equation describes variables that are directly proportional. y = 5x
Which of the following is true if x has a negative value and is increased from -5 to -2?

A) The value of y will decrease.
B) The value of y will increase.
C) The value of y will no longer be proportional to the value of x.
D) The value of y will remain the same.

Question 11

Which of the following is true about nonlinear graphs?

A) Extrapolation may be used to identify data outside the standard curve.
B) The process of interpolation can be applied to it.
C) The equation defining the data generally follows the model of y = mx + b.
D) The two variables measured are directly proportional to each other.

Question 12

In the phenomenon of proportionality,

A) a variable is independent of another variable.
B) multiple variables change independently of each other.
C) one variable changes in proportion to another.
D) two variables can be controlled by the experimenter.

Question 13

In an equation,the independent variable is which of the following?

A) The variable that has a fixed value
B) The variable that is determined by the other variable
C) The variable whose value is changed by the proportionality constant
D) The variable whose value we control

Question 14

A scientist quantifies substance A in a flask where chemical reactions are occurring.A plot of the amount of product as a function of time is a straight line with a slope of -0.8 mmol/second.The negative value of the slope indicates what?

A) The amount of substance A in the flask is decreasing over time.
B) The amount of substance A in the flask is increasing over time.
C) The amount of substance A in the flask remains constant over time.
D) None of the above

Question 15

The following graph displays the rate of the production of X as a function of time.
Which equation represents the slope of this line?

A) $\frac{(16 \mathrm{mmol}-10 \mathrm{mmol})}{(7 \mathrm{~s}-4 \mathrm{~s})}$
B) $\frac{(7 s-3 s)}{(16 \mathrm{mmol}-8 \mathrm{mmol})}$
C) $\frac{(14 \mathrm{mmol}-6 \mathrm{~s})}{(8 \mathrm{mmol}-3 \mathrm{~s})}$
D) $\frac{(8 \mathrm{mmol}-16 \mathrm{mmol})}{(3 \mathrm{~s}-7 \mathrm{~s})}$

Question 16

The following graph is the standard curve for absorbance of an analyte.
In the laboratory,you are presented with a solution with an unknown concentration of the analyte.You measure the absorbance of the solution and determine it to be 0.75.Can the analyte's concentration in the solution be determined using this standard curve?

A) No, because glucose concentrations cannot exceed 0.016 mg/ml.
B) No, because the concentration must be extrapolated.
C) Yes, because the concentration can be interpolated.
D) Yes, because the standard curve is linear.

Question 17

The following equation represents two directly proportional variables. y = 4x + 3
What is the value of the slope of the line generated by this equation?

A) 0
B) 3
C) 4
D) It cannot be determined.

Question 18

Consider the following equation: y = 2x
Which of the following is the proportionality constant?

A) 2
B) 4
C) x
D) y

Question 19

Consider the following equation: y = 2x + 4
What is the value of the y-intercept?

A) 0
B) 2
C) 4
D) 8