Q: How many atoms are in 2.00 moles of carbon?

$$2.00 \times 6.022 \times 10$$^{23}$$ = 1.20 \times 10$$^{24}$$ atoms

Q: A sample contains 0.500 mol of water molecules. How many molecules are present?

$$0.500 \times 6.022 \times 10$$^{23}$$ = 3.01 \times 10$$^{23}$$ molecules

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically bonded in fixed proportions.

Question 2

Which property is classified as intensive?

Accepted Answer

Density

Question 3

A sample contains 3.00 g of substance X and occupies 2.00 cm$$^3. $$What is the density of substance X?

Accepted Answer

$$D = \frac{3.00}{2.00} = 1.50\ \mathrm{g/cm^3$}$$

Question 4

Which of the following is a physical property?

Accepted Answer

Melting point

Question 5

Which statement best describes the law of conservation of matter?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 6

A student measures the mass of a gold nugget to be 15.0 g and its volume to be 0.78 cm$$^3. $$What is the density of gold in this sample?

Accepted Answer

$$D = \frac{15.0}{0.78} = 19.2\ \mathrm{g/cm^3$}$$

Question 7

Which of the following best represents a heterogeneous mixture?

Accepted Answer

Salad with lettuce, tomatoes, and cucumbers

Question 8

Which of the following is the correct symbol for an atom with 17 protons, 18 neutrons, and a -1 charge?

Accepted Answer

$$^{35}_{17}\mathrm{Cl}^{-}$$

Question 9

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 10

A sample of chlorine contains 75.53% $$^{35}Cl ($$atomic mass = 34.97 amu) and 24.47% $$^{37}Cl ($$atomic mass = 36.97 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45\ \mathrm{amu}$$

Question 11

Which of the following best describes the difference between mass and weight?

Accepted Answer

Mass is the amount of matter in an object, weight is the force exerted by gravity on that mass.

Question 12

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

Accepted Answer

Rusting of iron

Question 13

How many atoms are in 2.00 moles of carbon?

Accepted Answer

$$2.00 	imes 6.022 	imes 10$$^{23}$$ = 1.20 	imes 10$$^{24}$$ atoms

Question 14

Which of the following is the correct empirical formula for glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$$)?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 15

Which of the following best describes the symbolic domain in chemistry?

Accepted Answer

It is the representation of chemical phenomena using symbols, formulas, and equations.

Question 16

A sample contains 0.500 mol of water molecules. How many molecules are present?

Accepted Answer

$$0.500 	imes 6.022 	imes 10$$^{23}$$ = 3.01 	imes 10$$^{23}$$ molecules

Question 17

Which experiment led to the discovery that atoms are mostly empty space with a dense, positively charged nucleus?

Accepted Answer

Rutherford gold foil experiment

Question 18

Which of the following is NOT a pure substance?

Accepted Answer

Milk

Question 19

Which of the following is the correct relationship for converting mass to moles?

Accepted Answer

$$n = \frac{m}{MM}$$

Question 20

A sample of $$\mathrm{C}_2\mathrm{H}_6$$ contains 30.0 g. How many moles of $$\mathrm{C}_2\mathrm{H}_6$$ are present? (Molar mass = 30.07 g/mol)

Accepted Answer

$$\frac{30.0}{30.07} = 0.998$$ mol

Foundations of General Chemistry: Matter, Measurement, and Atomic Structure

Guida di studio - Domande di pratica

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