Question 1

A student measures the mass of a sample three times and records 12.34 g, 12.35 g, and 12.33 g. Which of the following best describes the precision and accuracy of these measurements?

Accepted Answer

The measurements are precise but may not be accurate.

Question 2

How many significant figures are in the measurement 0.0040700 g?

Accepted Answer

6

Question 3

Which of the following numbers contains three significant figures?

Accepted Answer

0.00604

Question 4

A student adds 12.11 g, 0.034 g, and 1.2 g. What is the sum, rounded to the correct number of decimal places?

Accepted Answer

$$13.3\ \mathrm{g}$$

Question 5

Which of the following is the correct conversion factor to convert pounds (lbs) to kilograms (kg)?

Accepted Answer

$$\frac{1\ \mathrm{kg}}{2.205\ \mathrm{lbs}}$$

Question 6

A patient’s temperature is measured as 39.0 $$^\circC. $$What is this temperature in Kelvin?

Accepted Answer

$$312.2\ \mathrm{K}$$

Question 7

Which of the following best describes the difference between heat and temperature?

Accepted Answer

Heat is the total energy of molecular motion, while temperature is a measure of the average energy of molecular motion.

Question 8

A 50.0 g sample of metal absorbs 120 cal of heat, causing its temperature to rise from 20.0 $$^\circC to 44.0$$ $$^\circC. $$What is the specific heat of the metal?

Accepted Answer

$$0.10\ \mathrm{cal}/\mathrm{g}\cdot^\circ\mathrm{C}$$

Question 9

Which of the following statements about significant figures is correct?

Accepted Answer

Zeros between nonzero digits are always significant.

Question 10

A nutrition label states that a food contains 250 Calories. How many joules of energy does this represent? (1 cal = 4.184 J)

Accepted Answer

$$1,046,000\ \mathrm{J}$$

Question 11

A nurse needs to convert a patient’s body temperature from 102.2 $$^\circF to$$ $$^\circC. $$What is the patient’s temperature in Celsius?

Accepted Answer

$$39.0\ ^\circ\mathrm{C}$$

Question 12

Which of the following best explains why a graduated cylinder is more precise than a beaker for measuring volume?

Accepted Answer

A graduated cylinder has finer calibration marks, allowing for more accurate and precise readings.

Question 13

A sample of water is heated from 25.0 $$^\circC to 75.0$$ $$^\circC. If $$the mass of water is 100.0 g and the specific heat is $$1.00\ \mathrm{cal}/\mathrm{g}\cdot^\circ\mathrm{C}$$, how much heat is absorbed?

Accepted Answer

$$5,000\ \mathrm{cal}$$

Question 14

Which of the following is an exact number?

Accepted Answer

The number of students in a classroom

Question 15

A laboratory technician needs to prepare 250.0 mL of a solution. If the technician uses a beaker marked every 50 mL, what is the best way to ensure the correct volume is measured?

Accepted Answer

Use a graduated cylinder for greater precision.

Question 16

A student multiplies $$2.34 (3 $$sig figs) by $$1.2 (2 $$sig figs). What is the correct answer, rounded to the proper number of significant figures?

Accepted Answer

$$2.8$$

Question 17

Which of the following best describes the relationship between the Celsius and Kelvin temperature scales?

Accepted Answer

A change of $$1\ ^\circ\mathrm{C} is $$equal to a change of $$1\ \mathrm{K}.$$

Question 18

A 150.0 lb patient is weighed in a hospital. What is the patient’s mass in kilograms, rounded to the correct number of significant figures? ($$1\ \mathrm{kg} = 2.205\ \mathrm{lb})$$

Accepted Answer

$$68.03\ \mathrm{kg}$$

Question 19

Which of the following best explains why equal amounts of heat energy raise the temperature of different substances to different extents?

Accepted Answer

Different substances have different specific heats.

Measurement, Significant Figures, Unit Conversions, and Energy in Chemistry

Guida di studio - Domande di pratica

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