Question 1

Which of the following elements is classified as a halogen on the periodic table?

Accepted Answer

Chlorine

Question 2

A student measures the mass of a sample as 12.50 g and its volume as 5.0 mL. What is the density of the sample, and which significant figures rule applies to the answer?

Accepted Answer

Density = $$2.5\ \mathrm{g/mL}$$, rounded to two significant figures because of the volume measurement.

Question 3

Which of the following is the correct electron configuration for a sodium ion ($$\mathrm{Na^+}$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 4

Which of the following is a correct formula for a polyatomic ion?

Accepted Answer

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

Question 5

A radioactive isotope undergoes beta particle emission. What happens to its atomic number and mass number?

Accepted Answer

Atomic number increases by 1; mass number remains unchanged.

Question 6

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

Accepted Answer

Accuracy refers to how close measurements are to the true value; precision refers to how close measurements are to each other.

Question 7

Which of the following is the correct Lewis structure for a molecule of $$\mathrm{O_2$}$$?

Accepted Answer

Two oxygen atoms connected by a double bond with four lone pairs.

Question 8

Which of the following acids is correctly named and formulated?

Accepted Answer

Hydrochloric acid, $$\mathrm{HCl}$$

Question 9

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$\mathrm{NaCl}$$ molar mass = $$58.44\ \mathrm{g/mol})$$

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 10

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 11

Which of the following ions has the same electron configuration as neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{Na^+}$$

Question 12

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 13

A sample contains $$2.0 	imes 10$$^{23}$$ atoms of magnesium. How many moles of magnesium are present? (1$$\ \mathrm{mol} = 6.022 	imes $$10^{23}$$ atoms)

Accepted Answer

$$0.33\ \mathrm{mol}$$

Question 14

Which of the following best describes the color observed in a spectrophotometry experiment?

Accepted Answer

The color observed is the color transmitted by the solution.

Question 15

Which of the following is the correct name and formula for a base?

Accepted Answer

Sodium hydroxide, $$\mathrm{NaOH}$$

Question 16

Which of the following elements is an alkaline earth metal?

Accepted Answer

Calcium

Question 17

Which of the following is the correct formula for the nitrate ion?

Accepted Answer

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

Question 18

Which of the following is a correct statement about the atomic number?

Accepted Answer

The atomic number is the number of protons in the nucleus.

Question 19

Which of the following is the correct formula for the compound formed between magnesium and chlorine?

Accepted Answer

$$\mathrm{$$MgCl_2$$}$$

Foundational Topics in GOB Chemistry: Elements, Atomic Structure, and Measurement

Guida di studio - Domande di pratica

Study guide - Flashcard