,Portage Learning CHEM 103 General
Chemistry I Module 1 Exam
Question 1
Which of the following values represents the number 0.000451 correctly expressed in
scientific notation?
A. 4.51 x 10^-4
B. 45.1 x 10^-5
C. 4.51 x 10^4
D. 0.451 x 10^-3
Answer:
A. 4.51 x 10^-4
Rationale:
To convert a number less than 1 into scientific notation, the decimal point must move to
the right until it is placed after the first non-zero digit. For 0.000451, the decimal moves
4 places to the right to get 4.51. Because the original number is less than 1, the
exponent must be negative, resulting in 4.51 x 10^-4.
Question 2
A student calculates the density of an unknown liquid by dividing its mass (24.01 g) by
its volume (12.0 mL). How many significant figures should be present in the final
calculated density value?
A. 2
B. 3
C. 4
D. 5
Answer:
B. 3
Rationale:
When performing multiplication or division, the rule for significant figures states that the
, final answer cannot have more significant figures than the measurement with the fewest
significant figures. The mass (24.01 g) has 4 significant figures, while the volume (12.0
mL) has 3 significant figures. Therefore, the final answer must be limited to 3 significant
figures.
Question 3
Convert a recorded temperature of 95.0 °F to the Kelvin scale.
A. 35.0 K
B. 238.2 K
C. 308.2 K
D. 368.2 K
Answer:
C. 308.2 K
Rationale:
First, convert Fahrenheit to Celsius using the formula °C = (°F - 32) / 1.8. Substituting
95.0 °F yields (95.0 - 32) / 1.8 = 35.0 °C. Next, convert Celsius to Kelvin using the
formula K = °C + 273.15. Adding 35.0 °C + 273.15 equals 308.15 K, which rounds to
308.2 K based on standard decimal place addition rules.
Question 4
How should a cup of hot black coffee with completely dissolved sugar be classified
under the categories of matter?
A. Element
B. Compound
C. Homogeneous mixture
D. Heterogeneous mixture
Answer:
C. Homogeneous mixture
Rationale:
A homogeneous mixture, also known as a solution, has a completely uniform
Chemistry I Module 1 Exam
Question 1
Which of the following values represents the number 0.000451 correctly expressed in
scientific notation?
A. 4.51 x 10^-4
B. 45.1 x 10^-5
C. 4.51 x 10^4
D. 0.451 x 10^-3
Answer:
A. 4.51 x 10^-4
Rationale:
To convert a number less than 1 into scientific notation, the decimal point must move to
the right until it is placed after the first non-zero digit. For 0.000451, the decimal moves
4 places to the right to get 4.51. Because the original number is less than 1, the
exponent must be negative, resulting in 4.51 x 10^-4.
Question 2
A student calculates the density of an unknown liquid by dividing its mass (24.01 g) by
its volume (12.0 mL). How many significant figures should be present in the final
calculated density value?
A. 2
B. 3
C. 4
D. 5
Answer:
B. 3
Rationale:
When performing multiplication or division, the rule for significant figures states that the
, final answer cannot have more significant figures than the measurement with the fewest
significant figures. The mass (24.01 g) has 4 significant figures, while the volume (12.0
mL) has 3 significant figures. Therefore, the final answer must be limited to 3 significant
figures.
Question 3
Convert a recorded temperature of 95.0 °F to the Kelvin scale.
A. 35.0 K
B. 238.2 K
C. 308.2 K
D. 368.2 K
Answer:
C. 308.2 K
Rationale:
First, convert Fahrenheit to Celsius using the formula °C = (°F - 32) / 1.8. Substituting
95.0 °F yields (95.0 - 32) / 1.8 = 35.0 °C. Next, convert Celsius to Kelvin using the
formula K = °C + 273.15. Adding 35.0 °C + 273.15 equals 308.15 K, which rounds to
308.2 K based on standard decimal place addition rules.
Question 4
How should a cup of hot black coffee with completely dissolved sugar be classified
under the categories of matter?
A. Element
B. Compound
C. Homogeneous mixture
D. Heterogeneous mixture
Answer:
C. Homogeneous mixture
Rationale:
A homogeneous mixture, also known as a solution, has a completely uniform
