Q: A patient is given 250 mg of a medication. If the molar mass of the medication is 500 g/mol, how many moles of the medication did the patient receive?

$$ \frac{0.250}{500} = 0.0005 \text{ mol} $$

Q: A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

$$ \frac{10.0}{58.44} = 0.171 \text{ mol}; \frac{0.171}{0.500} = 0.342 \text{ M} $$

Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element is a pure substance made of only one kind of atom, while a compound consists of two or more elements chemically combined in fixed proportions.

Question 2

A patient is given 250 mg of a medication. If the molar mass of the medication is 500 g/mol, how many moles of the medication did the patient receive?

Accepted Answer

$$ \frac{0.250}{500} = 0.0005 	ext{ mol} $$

Question 3

Which of the following statements about ionic and covalent bonds is correct?

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, while covalent bonds involve the sharing of electrons between atoms.

Question 4

A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$ \frac{10.0}{58.44} = 0.171 	ext{ mol}; \frac{0.171}{0.500} = 0.342 	ext{ M} $$

Question 5

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

Water has a bent molecular shape and an uneven distribution of electrons, resulting in a partial positive charge on hydrogen and a partial negative charge on oxygen.

Question 6

A chemical reaction has the following balanced equation: $$ 2H_2 + O_2$ \rightarrow 2H_2O . If $$you start with 4 moles of $$ H_2$ $$ and 2 moles of $$ O_2$ $$, how many moles of $$ H_2O $$ can be produced?

Accepted Answer

4 moles of $$ H_2O $$

Question 7

Which of the following is a correct statement about acids and bases according to the Bronsted-Lowry definition?

Accepted Answer

An acid is a proton donor and a base is a proton acceptor.

Question 8

A buffer solution is important in biological systems because:

Accepted Answer

It resists changes in pH when small amounts of acid or base are added.

Question 9

Which of the following factors will increase the rate of a chemical reaction?

Accepted Answer

Increasing the temperature.

Question 10

A patient’s blood pH is measured at 7.1. Which of the following best describes this condition?

Accepted Answer

The patient is experiencing acidosis, as normal blood pH is about 7.4.

Question 11

Which of the following is the correct electron configuration for a neutral atom of sodium ($$ Na $$)?

Accepted Answer

$$ 1s^2$ 2s^2$ 2p^6$ 3s^1$ $$

Question 12

Which of the following best describes the process of osmosis?

Accepted Answer

The movement of water molecules from an area of low solute concentration to an area of high solute concentration through a semipermeable membrane.

Question 13

Which of the following is a correct statement about isotopes?

Accepted Answer

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

Question 14

A sample of gas occupies 2.0 L at 1.0 atm pressure. If the pressure is increased to 2.0 atm at constant temperature, what will be the new volume of the gas?

Accepted Answer

$$ P_1V_1 = P_2V_2 \Rightarrow (1.0)(2.0) = (2.0)V_2$ \Rightarrow V_2$ = 1.0 	ext{ L} $$

Question 15

Which of the following is a correct example of a redox reaction?

Accepted Answer

$$ 2Na + Cl_2$ \rightarrow 2NaCl $$

Question 16

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst lowers the activation energy, increasing the rate of the reaction without being consumed.

Question 17

Which of the following is the correct formula for calculating the percent composition by mass of an element in a compound?

Accepted Answer

$$ \frac{	ext{mass of element in 1 mol of compound}}{	ext{molar mass of compound}} 	imes 100\% $$

Question 18

A 0.1 M solution of $$ HCl $$ has a pH of:

Accepted Answer

$$ pH = -\log[H^+] = -\log(0.1) = 1 $$

Question 19

Which of the following is a correct statement about the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve a full set of eight valence electrons.

GOB Chemistry Course Syllabus: Outcomes and Module Learning Objectives

Guida di studio - Domande di pratica

Study guide - Flashcard