Q: How many atoms are present in 0.250 mol of copper ($$\mathrm{Cu}$$)? ($$N_A = 6.022 \times 10$$^{23}$$\ \mathrm{mol}^{-1})$$

$$1.51 \times 10$$^{23}$$ atoms

Q: A laser emits light with a wavelength of $$500\ \mathrm{nm}. $$What is the energy of a single photon of this light? ($$h = 6.626 \times 10$$^{-34}$$\ \mathrm{J\cdot s}$$, $$c = 3.00 \times 10^8$\ \mathrm{m/s})$$

$$3.98 \times 10$$^{-19}$$\ \mathrm{J}$$

Q: A patient receives 250 mg of a medication. If the molar mass of the drug is $$500\ \mathrm{g/mol}$$, how many moles of the drug did the patient receive?

$$5.0 \times 10$$^{-4}$$\ \mathrm{mol}$$

Question 1

Which of the following statements correctly describes the three subatomic particles in an atom?

Accepted Answer

Protons and neutrons have nearly equal masses, while electrons have much less mass.

Question 2

Which of the following is the correct symbol for an isotope of carbon with 6 protons, 8 neutrons, and a neutral charge?

Accepted Answer

$$^{14}_{6}\mathrm{C}$$

Question 3

A sample of magnesium contains 78.99% $$^{24}\mathrm{Mg} (23.985 $$amu), 10.00% $$^{25}\mathrm{Mg} (24.986 $$amu), and 11.01% $$^{26}\mathrm{Mg} (25.983 $$amu). What is the average atomic mass of magnesium?

Accepted Answer

$$24.31\ \mathrm{amu}$$

Question 4

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 each atom in a molecule, while an empirical formula shows the simplest whole-number ratio of atoms.

Question 5

According to the periodic law, how are elements arranged in the modern periodic table?

Accepted Answer

By increasing atomic number in rows (periods) and columns (groups) with similar properties.

Question 6

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

Accepted Answer

A piece of iron rusting in moist air.

Question 7

Which of the following is an extensive property of matter?

Accepted Answer

Mass

Question 8

A student measures the mass of a sample as 12.345 g and the volume as 6.7 mL. What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$1.8\ \mathrm{g/mL}$$

Question 9

Convert 25.0 $$^{\circ}\mathrm{C} to $$Kelvin.

Accepted Answer

$$298.2\ \mathrm{K}$$

Question 10

How many atoms are present in 0.250 mol of copper ($$\mathrm{Cu}$$)? ($$N_A = 6.022 	imes 10$$^{23}$$\ \mathrm{mol}^{-1})$$

Accepted Answer

$$1.51 	imes 10$$^{23}$$ atoms

Question 11

Which of the following relationships correctly describes the speed of light ($$c$$), wavelength ($$\lambda$$), and frequency ($$
u) of $$electromagnetic radiation?

Accepted Answer

$$c = \lambda 
u$$

Question 12

A laser emits light with a wavelength of $$500\ \mathrm{nm}. $$What is the energy of a single photon of this light? ($$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s}$$, $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$3.98 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 13

According to the Bohr model, what happens when an electron in a hydrogen atom transitions from $$n=3 to$$ $$n=2$$?

Accepted Answer

A photon is emitted with energy equal to the difference between the two energy levels.

Question 14

Which set of quantum numbers is not allowed for an electron in an atom?

Accepted Answer

$$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 15

Which of the following elements is a metalloid?

Accepted Answer

Silicon ($$\mathrm{Si})$$

Question 16

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

Sodium nitrate ($$\mathrm{$$NaNO_3$$})$$

Question 17

A patient receives 250 mg of a medication. If the molar mass of the drug is $$500\ \mathrm{g/mol}$$, how many moles of the drug did the patient receive?

Accepted Answer

$$5.0 	imes 10$$^{-4}$$\ \mathrm{mol}$$

Question 18

Which of the following best describes a physical property?

Accepted Answer

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

Question 19

Which of the following is the correct order of electromagnetic radiation from lowest to highest energy?

Accepted Answer

Radio waves \u003c Visible light \u003c Ultraviolet \u003c Gamma rays

General Chemistry I: Unit 1 Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard