Q: How many atoms are in 2.00 moles of oxygen gas (O$$_2$$)?

$$2.41 \times 10$$^{24}$$ atoms

Question 1

A sample of water has a mass of 250 g. Convert this mass to kilograms using the correct SI prefix conversion.

Accepted Answer

$$0.25 	ext{ kg}$$

Question 2

Which of the following ions is correctly paired with its name?

Accepted Answer

NO$$_3^-$$: nitrate

Question 3

A compound contains 2.00 g of hydrogen and 16.00 g of oxygen. What is the mass ratio of hydrogen to oxygen, and which law does this illustrate?

Accepted Answer

1:8, Law of Definite Proportions

Question 4

How many significant figures are in the measurement 0.0045600?

Accepted Answer

6

Question 5

Which of the following is the correct name for the compound KNO$$_3$$?

Accepted Answer

potassium nitrate

Question 6

A student needs to convert 5.0 hours to seconds. What is the correct answer?

Accepted Answer

$$3.6 	imes 10^4$ 	ext{ s}$$

Question 7

Which of the following elements is a nonmetal?

Accepted Answer

Sulfur (S)

Question 8

What is the molar mass of ammonium sulfate, (NH$$_4$$)$$_2SO$_4$$?

Accepted Answer

$$132.14 	ext{ g/mol}$$

Question 9

Balance the following chemical equation: __ NH$$_3 + __ O$_2$$ → __ NO + __ H$$_2O$$

Accepted Answer

4 NH$$_3 + 5 O$_2$$ → 4 NO + 6 H$$_2O$$

Question 10

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of CO_2$. How many moles of CO_2$ are present?

Accepted Answer

$$0.50 	ext{ mol}$$

Question 11

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

Accepted Answer

MnO$$_4^-$$

Question 12

A compound is found to contain 40.0% sulfur and 60.0% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

SO$$_2$$

Question 13

Which law states that the total mass of reactants equals the total mass of products in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Question 14

How many protons, neutrons, and electrons are in $$^{35}Cl$^-$$?

Accepted Answer

17 protons, 18 neutrons, 18 electrons

Question 15

Which of the following is the correct name for the compound NaClO$$_4$$?

Accepted Answer

sodium perchlorate

Question 16

A student measures the mass of a sample as 12.30 g and the volume as 4.0 mL. What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$3.08 	ext{ g/mL}$$

Question 17

Which of the following is a binary covalent compound?

Accepted Answer

CO$$_2$$

Question 18

How many atoms are in 2.00 moles of oxygen gas (O$$_2$$)?

Accepted Answer

$$2.41 	imes 10$$^{24}$$ atoms

Question 19

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

Accepted Answer

PO$$_4$$^{3-}$$

Question 20

A solution contains 0.250 mol of Na$$_2SO$_4. $$How many formula units of Na$$_2SO$_4$$ are present?

Accepted Answer

$$1.51 	imes 10$$^{24}$$

General Chemistry Fundamentals: Units, Nomenclature, and Chemical Calculations

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