Q: How many copper atoms are in $$2.45$$ mol of copper?

$$1.48 \times 10$$^{24}$$ atoms

Question 1

Which of the following best describes the difference between a compound and a homogeneous mixture, as shown in the classification of matter diagram?

Accepted Answer

A compound contains two or more elements chemically bonded in fixed proportions, while a homogeneous mixture contains two or more substances physically combined in variable proportions.

Question 2

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

Accepted Answer

Water freezing to form ice.

Question 3

A student performs the calculation $$1.052 	imes 12.054 	imes 0.53$$ and obtains $$6.7208. $$According to the rules for significant figures, what is the correct answer?

Accepted Answer

$$6.7$$

Question 4

Which of the following statements about significant figures is correct?

Accepted Answer

Zeros between nonzero digits are always significant.

Question 5

A measurement is recorded as $$0.00023 m. $$How many significant figures does this value have?

Accepted Answer

2

Question 6

Convert $$1.8$$ quarts to cubic centimeters using the following relationships: $$1.057 qt$$ $$= 1 L$$, $$1 mL$$ $$= 10$$^{-3}$$ L, 1$ mL = 1$ cm^3$. What is the answer with the correct number of significant figures?

Accepted Answer

$$1.7 	imes 10^3$ cm^3$

Question 7

According to the law of multiple proportions, when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other element are:

Accepted Answer

In ratios of small whole numbers.

Question 8

Which subatomic particle determines the identity of an element?

Accepted Answer

The number of protons.

Question 9

A neutral atom of magnesium has an atomic number of 12 and a mass number of 25. How many protons, neutrons, and electrons does it have?

Accepted Answer

12 protons, 13 neutrons, 12 electrons

Question 10

How many electrons are present in a $$\mathrm{P$$^{3-}$$}$$ ion?

Accepted Answer

18

Question 11

Which group in the periodic table contains the alkali metals?

Accepted Answer

Group 1A

Question 12

Naturally occurring chlorine consists of $$75.77\%$$ chlorine-35 (mass $$34.97$$ amu) and $$24.23\%$$ chlorine-37 (mass $$36.97$$ amu). What is the atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 13

How many copper atoms are in $$2.45$$ mol of copper?

Accepted Answer

$$1.48 	imes 10$$^{24}$$ atoms

Question 14

A pencil lead contains $$0.0265 g of $$pure graphite (carbon). How many moles of carbon are present? (Molar mass of C = $$12.01 g/$$mol)

Accepted Answer

$$2.21 	imes 10$$^{-3}$$ mol

Question 15

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from a metal to a nonmetal.

Question 16

What is the empirical formula for a compound with the molecular formula $$C_6H_{12}O_6$?

Accepted Answer

$$CH_2O$$

Question 17

What is the correct name for the compound $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 18

Which of the following is the correct formula for aluminum oxide?

Accepted Answer

$$Al_2O_3$$

Question 19

A hydrate contains $$6$$ water molecules per formula unit. What is the correct prefix and name for this hydrate?

Accepted Answer

Hexa-, as in copper(II) sulfate hexahydrate

Question 20

If the atmospheric carbon dioxide concentration increased from $$320$$ ppm in $$1960 to$$ $$390$$ ppm in $$2010$$, what was the average rate of increase per year over this period?

Accepted Answer

$$1.4$$ ppm/year

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

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