Q: Avogadro’s number is:

$$6.02 \times 10$$^{23}$$ particles per mole

Question 1

Which of the following best describes the Law of Conservation of Mass as established by Antoine Lavoisier?

Accepted Answer

The total mass of substances present after a chemical reaction is equal to the mass before the reaction.

Question 2

The term 'atom' comes from the Greek word 'atomos,' which means:

Accepted Answer

cannot be cut

Question 3

A log burns completely in a campfire, and the mass of the ash is much less than the mass of the original log. According to the law of conservation of mass, what happened to the matter?

Accepted Answer

The matter that composed the log reacts to form gases that are released into the air.

Question 4

Which of the following is NOT a postulate of Dalton’s Atomic Theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 5

Which chemical law is illustrated by the following data: Compound A contains 1.333 g of oxygen per gram of carbon, whereas compound B contains 2.666 g of oxygen per gram of carbon?

Accepted Answer

The law of multiple proportions

Question 6

If compound A has an equal number of oxygen and carbon atoms, and compound B contains twice as much oxygen per gram of carbon, what can we conclude about compound B?

Accepted Answer

The second compound must have twice as many oxygen atoms per carbon atom as the first compound.

Question 7

Which statement best captures one of the differences between the law of definite proportions and the law of multiple proportions?

Accepted Answer

The law of definite proportions applies to two or more samples of the same compound, while the law of multiple proportions applies to two different compounds containing the same two elements.

Question 8

Which of the following best describes how Mendeleev arranged the elements in his early periodic table?

Accepted Answer

By similar chemical properties

Question 9

Avogadro’s number is:

Accepted Answer

$$6.02 	imes 10$$^{23}$$ particles per mole

Question 10

How many moles of $$CO_2$$ are in $$2.50 	imes 10$$^{24}$$ molecules of CO_2$?

Accepted Answer

$$4.15$$ moles

Question 11

What is the mass, in grams, of $$3.25$$ moles of ammonia, $$NH_3$$? (Molar mass of $$NH_3 = 17.03$ g/mol)

Accepted Answer

$$55.3 g$$

Question 12

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons, but different numbers of neutrons.

Question 13

Which of the following is correct?

Accepted Answer

All of the above

Question 14

A pure copper penny has $$2.81 	imes 10$$^{22}$$ atoms. If the molar mass of copper is 63.55$ g/mol, what is the mass of the penny?

Accepted Answer

$$1.30 g$$

Question 15

Which has more atoms: $$10.0 g of Mg or$$ $$10.0 g of Ca$$? (Atomic masses: Mg = $$24.31 g/$$mol, Ca = $$40.08 g/$$mol)

Accepted Answer

Magnesium

Question 16

Which of the following is an example of green chemistry?

Accepted Answer

Replacing mercury fluorescent light bulbs with efficient mercury-free light bulbs.

Question 17

What is the mass of $$2.55 	imes 10$$^{23}$$ atoms of lead (Pb$)? (Molar mass of Pb = 207.2$ g/mol)

Accepted Answer

$$87.9 g$$

Question 18

Which of the following reactions is consistent with Dalton’s Atomic Theory?

Accepted Answer

$$C + H_2$ \rightarrow CH_4$

Question 19

Which group of the periodic table contains the alkaline earth metals?

Accepted Answer

Group 2

Atoms, Laws of Chemical Combination, and the Periodic Table: Foundations of Modern Chemistry

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