Question 1

A laboratory technician measures the mass of a metal sample as 12.34 g and its volume as 4.56 mL. What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$$2.7\,\mathrm{g/mL}$$

Question 2

Which of the following statements best describes the difference between precision and accuracy in scientific measurements?

Accepted Answer

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close a measurement is to the true value.

Question 3

A student records the following measurements for the length of a table: 1.234 m, 1.235 m, and 1.233 m. The actual length is 1.200 m. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 4

Which of the following is a derived SI unit?

Accepted Answer

$$\mathrm{m^3$} ($$cubic meter)

Question 5

A chemist needs to convert 250.0 mL of a solution to liters using dimensional analysis. What is the correct answer?

Accepted Answer

$$0.2500\,\mathrm{L}$$

Question 6

Which of the following best describes the quantum-mechanical model of the atom?

Accepted Answer

It describes electrons as existing in probability clouds called orbitals, rather than fixed orbits.

Question 7

Which quantum number determines the energy level (shell) of an electron in an atom?

Accepted Answer

$$n$$

Question 8

According to the uncertainty principle, which of the following is true about an electron in an atom?

Accepted Answer

It is impossible to know both the exact position and exact velocity of the electron at the same time.

Question 9

Which of the following is NOT an SI base unit?

Accepted Answer

$$\mathrm{liter}$$

Question 10

A sample of a compound contains only hydrogen and oxygen atoms. Which of the following statements is correct?

Accepted Answer

The sample is a compound because it contains atoms of different elements bonded together.

Question 11

Which of the following best describes a photon?

Accepted Answer

A quantum of electromagnetic radiation.

Question 12

The de Broglie relation links the wavelength of a particle to its momentum. Which equation expresses this relationship?

Accepted Answer

$$\lambda = \frac{h}{p}$$

Question 13

A student is asked to calculate the energy of a photon with a frequency of $$6.00 	imes 10$$^{14}$$\,\mathrm{Hz}. $$Which equation should they use?

Accepted Answer

$$E = h
u$$

Question 14

Which of the following statements about matter is correct?

Accepted Answer

Matter is anything that takes up space and has mass.

Question 15

A hospital stores liquid oxygen in a tank with a mass of $$500.0\,\mathrm{kg}$$ and a volume of $$450.0\,\mathrm{L}. $$What is the density of the liquid oxygen in $$\mathrm{g/mL}$$?

Accepted Answer

$$1.11\,\mathrm{g/mL}$$

Question 16

Which of the following is the correct set of quantum numbers for an electron in a 3p orbital?

Accepted Answer

$$n=3,\ l=1,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 17

A nurse needs to administer a medication at a dose of $$0.250\,\mathrm{mg/kg} to a $$patient weighing $$70.0\,\mathrm{kg}. $$How many milligrams of medication should be given?

Accepted Answer

$$17.5\,\mathrm{mg}$$

Question 18

Which of the following best describes an element?

Accepted Answer

A pure substance made of only one kind of atom.

Question 19

Which of the following is the correct speed of light in a vacuum?

Accepted Answer

$$3.00 	imes 10^8$\,\mathrm{m/s}$$

Question 20

A scientist measures the temperature of a reaction as $$25.0\,^{\circ}\mathrm{C}. $$What is this temperature in kelvin?

Accepted Answer

$$298.2\,\mathrm{K}$$

Unit 1 Review: Units, Measurement, Atoms, and the Quantum-Mechanical Model

Guida di studio - Domande di pratica

Study guide - Flashcard