Q: A sample of mercury has a volume of 50.0 mL. If the density of mercury is $13.6 \ \mathrm{g/cm^3}$, what is the mass of the sample in grams?

$m = d \times V = 13.6 \times 50.0 = 680$ g

Q: A student needs to convert 2.00 ft to centimeters. Which of the following is the correct sequence of conversion factors to use?

$2.00 \ \mathrm{ft} \times \frac{12 \ \mathrm{in}}{1 \ \mathrm{ft}} \times \frac{2.54 \ \mathrm{cm}}{1 \ \mathrm{in}}$

Question 1

A scientist measures the mass of a sample as 0.00430 g. How many significant figures are in this measurement?

Accepted Answer

3

Question 2

Which of the following is an example of a qualitative observation?

Accepted Answer

The solution changed from blue to green.

Question 3

A student records a temperature of 25.0 $^\circ$C. What is this temperature in kelvin?

Accepted Answer

$25.0 + 273.15 = 298.15$ K

Question 4

Which SI base unit is correctly matched with its physical quantity?

Accepted Answer

Mass: kilogram (kg)

Question 5

A sample of mercury has a volume of 50.0 mL. If the density of mercury is $13.6 \ \mathrm{g/cm^3}$, what is the mass of the sample in grams?

Accepted Answer

$m = d 	imes V = 13.6 	imes 50.0 = 680$ g

Question 6

Which temperature scale has no negative values?

Accepted Answer

Kelvin

Question 7

Convert 3.50 km to meters using the correct conversion factor.

Accepted Answer

$3.50 	imes 10^3 = 3500$ m

Question 8

A student adds 12.11 g, 18.0 g, and 1.013 g. What is the sum reported to the correct number of significant figures?

Accepted Answer

31.1 g

Question 9

Which of the following best describes the energy change when ice melts in your hand?

Accepted Answer

Endothermic; the system (ice) absorbs heat from your hand

Question 10

Which prefix multiplier is most appropriate for reporting a measurement of $5.57 	imes 10^{-6}$ m?

Accepted Answer

micro

Question 11

A Mars orbiter mission failed because engineers used pound-seconds instead of newton-seconds. What conversion factor should have been used to convert pound-seconds to newton-seconds?

Accepted Answer

$1 \ \mathrm{pound \cdot second} = 4.45 \ \mathrm{newton \cdot second}$

Question 12

Which of the following is an example of an exact value?

Accepted Answer

1 dozen = 12 items

Question 13

A student multiplies $2.50$ m by $3.0$ m. What is the answer reported with the correct number of significant figures?

Accepted Answer

$7.5 \ \mathrm{m^2}$

Question 14

Which of the following statements about density is correct?

Accepted Answer

Density is an intensive property and does not depend on the amount of substance.

Question 15

A copper sample is heated from room temperature to $95^\circ$C. What happens to its density?

Accepted Answer

The sample expands and its density decreases.

Question 16

Which of the following is the correct scientific notation for the number 0.0310 with the correct number of significant figures?

Accepted Answer

$3.10 	imes 10^{-2}$

Question 17

Which type of energy is stored in the chemical bonds of gasoline?

Accepted Answer

Potential energy

Question 18

The burning of natural gas in a stove is an example of which type of process, and what is the sign of the energy change for the system?

Accepted Answer

Exothermic; negative

Question 19

A student needs to convert 2.00 ft to centimeters. Which of the following is the correct sequence of conversion factors to use?

Accepted Answer

$2.00 \ \mathrm{ft} 	imes \frac{12 \ \mathrm{in}}{1 \ \mathrm{ft}} 	imes \frac{2.54 \ \mathrm{cm}}{1 \ \mathrm{in}}$

Question 20

Which of the following best describes the First Law of Thermodynamics?

Accepted Answer

Energy of the universe is conserved; it cannot be created or destroyed.

Essentials of Units, Measurements, and Problem Solving in Chemistry

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