Q: Which of the following numbers is correctly expressed in scientific notation?

$$0.00056 = 5.6 \times 10$$^{-4}$$

Q: Using the cross-method for unit conversion, how many centimeters are in $$2.5$$ meters? ($$1\ \mathrm{m} = 100\ \mathrm{cm})$$

$$2.5\ \mathrm{m} \times \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 250\ \mathrm{cm}$$

Q: A sample contains $$60\%$$ chlorine-35 and $$40\%$$ chlorine-37. What is the average atomic mass of chlorine? (Atomic masses: $$\mathrm{Cl-35} = 34.97\ \mathrm{u}$$, $$\mathrm{Cl-37} = 36.97\ \mathrm{u})$$

$$(0.60 \times 34.97) + (0.40 \times 36.97) = 35.77\ \mathrm{u}$$

Question 1

Which of the following statements best describes a scientific hypothesis?

Accepted Answer

A hypothesis is a testable and falsifiable statement that predicts the outcome of an experiment.

Question 2

Which of the following is an example of a physical property?

Accepted Answer

The melting point of ice at $$0\ ^\circ \mathrm{C}.$$

Question 3

A mixture of sand and salt is best classified as:

Accepted Answer

A heterogeneous mixture

Question 4

Which of the following changes is a chemical change?

Accepted Answer

Burning wood in a campfire

Question 5

How many significant figures are in the measurement $$0.00720$$?

Accepted Answer

3

Question 6

Which of the following numbers is correctly expressed in scientific notation?

Accepted Answer

$$0.00056 = 5.6 	imes 10$$^{-4}$$

Question 7

Using the cross-method for unit conversion, how many centimeters are in $$2.5$$ meters? ($$1\ \mathrm{m} = 100\ \mathrm{cm})$$

Accepted Answer

$$2.5\ \mathrm{m} 	imes \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 250\ \mathrm{cm}$$

Question 8

According to the Law of Definite Proportions, which statement is true?

Accepted Answer

A compound always contains the same elements in the same ratio by mass.

Question 9

An atom of carbon-14 has how many neutrons? (Atomic number of carbon = $$6$$, mass number = $$14)$$

Accepted Answer

$$8$$

Question 10

Which group in the periodic table contains elements that are most likely to form cations with a $$+1$$ charge?

Accepted Answer

Group 1 (alkali metals)

Question 11

What is the correct formula for strontium nitrate?

Accepted Answer

$$\mathrm{Sr(NO_3$)_2}$$

Question 12

Which of the following is the correct name for $$\mathrm{CO_2$}$$?

Accepted Answer

Carbon dioxide

Question 13

A sample contains $$60\%$$ chlorine-35 and $$40\%$$ chlorine-37. What is the average atomic mass of chlorine? (Atomic masses: $$\mathrm{Cl-35} = 34.97\ \mathrm{u}$$, $$\mathrm{Cl-37} = 36.97\ \mathrm{u})$$

Accepted Answer

$$(0.60 	imes 34.97) + (0.40 	imes 36.97) = 35.77\ \mathrm{u}$$

Question 14

Which of the following ions is a polyatomic ion?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 15

What is the charge on the copper ion in copper(II) oxide?

Accepted Answer

$$+2$$

Question 16

Which of the following best describes an amorphous solid?

Accepted Answer

A solid with no long-range order in its atomic arrangement.

Question 17

What is the correct name for $$\mathrm{$$CaCO_3$$}$$?

Accepted Answer

Calcium carbonate

Question 18

Which of the following is a correct application of the Law of Multiple Proportions?

Accepted Answer

Two elements can combine in different ratios to form different compounds.

Question 19

If you have $$3.5$$ grams of a substance and subtract $$2.396$$ grams, how many significant figures should your answer have?

Accepted Answer

2

Question 20

Which of the following is the correct formula for hydrogen sulfate?

Accepted Answer

$$\mathrm{$$HSO_4$$^-}$$

Foundations of General Chemistry: Matter, Measurement, and Atomic Structure

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