Q: A patient receives 250 mg of a medication. Convert this mass to grams using dimensional analysis.

$$250 \times \frac{1}{1000} = 0.25 g$$

Q: A sample contains 3.0 moles of $$NaCl. $$What is the mass of this sample? (Molar mass of $$NaCl = 58.44 g/$$mol)

$$3.0 \times 58.44 = 175.32 g$$

Question 1

Which of the following is an example of a chemical change?

Accepted Answer

A piece of iron rusting when left outside

Question 2

Which of the following is an intensive property?

Accepted Answer

Density

Question 3

A sample of a compound contains 40.0 g of carbon and 53.3 g of oxygen. What is the mass ratio of oxygen to carbon in this compound?

Accepted Answer

$$\frac{53.3}{40.0} = 1.33:1$$

Question 4

Which statement best describes the Law of Conservation of Mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 5

How many significant figures are in the measurement 0.004560 g?

Accepted Answer

4

Question 6

A patient receives 250 mg of a medication. Convert this mass to grams using dimensional analysis.

Accepted Answer

$$250 	imes \frac{1}{1000} = 0.25 g$$

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 8

Which of the following is the correct empirical formula for a compound with the molecular formula $$C_6H_{12}O_6$?

Accepted Answer

$$CH_2O$$

Question 9

What is the correct name for the compound $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 10

Which of the following best describes a mixture?

Accepted Answer

A substance composed of two or more substances physically combined

Question 11

Which of the following is a binary covalent compound?

Accepted Answer

$$CO_2$$

Question 12

Which of the following acids is correctly named?

Accepted Answer

HCl: Hydrochloric acid

Question 13

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

12

Question 14

Which of the following best describes the Law of Multiple Proportions?

Accepted Answer

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers.

Question 15

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

Accepted Answer

$$Al_2$$($$SO_4)_3$

Question 16

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 17

A sample contains 3.0 moles of $$NaCl. $$What is the mass of this sample? (Molar mass of $$NaCl = 58.44 g/$$mol)

Accepted Answer

$$3.0 	imes 58.44 = 175.32 g$$

Question 18

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 19

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms of each element, while an empirical formula shows the simplest whole-number ratio.

Question 20

A compound is found to contain 63.5% silver, 8.2% nitrogen, and 28.3% oxygen by mass. What is the empirical formula of this compound? (Ag = 107.9 g/mol, N = 14.0 g/mol, O = 16.0 g/mol)

Accepted Answer

$$AgNO_3$$

GOB Chemistry Exam #1 Study Guidance

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