Q: What is the correct formula for calculating the average atomic weight of an element with two isotopes, A and B, with masses $$m_A$$ and $$m_B$$ and abundances $$p_A$$ and $$p_B$$?

$$p_A \times m_A + p_B \times m_B$$

Question 1

Which of the following statements best describes the Law of Multiple Proportions?

Accepted Answer

If two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in the ratio of small whole numbers.

Question 2

Which experiment led to the discovery of the electron?

Accepted Answer

Cathode ray tube experiment

Question 3

What is the correct formula for calculating the average atomic weight of an element with two isotopes, A and B, with masses $$m_A$$ and $$m_B$$ and abundances $$p_A$$ and $$p_B$$?

Accepted Answer

$$p_A 	imes m_A + p_B 	imes m_B$$

Question 4

Which of the following is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms are indivisible and cannot be broken down into smaller particles.

Question 5

A sample of carbon contains 98.9% $$^{12}C ($$mass = 12.000 amu) and 1.1% $$^{13}C ($$mass = 13.003 amu). What is the atomic weight of carbon? (Round to two decimal places)

Accepted Answer

$$12.01$$

Question 6

Which of the following elements is a metalloid?

Accepted Answer

Silicon (Si)

Question 7

Which of the following compounds is an example of a binary molecular compound?

Accepted Answer

CO$$_2$$

Question 8

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

Accepted Answer

Iron(III) chloride

Question 9

Which of the following is the empirical formula for glucose ($$C_6H_{12}O_6$)?

Accepted Answer

$$CH_2O$$

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 is the correct formula for ammonium sulfate?

Accepted Answer

$$(NH_4$)_2SO_4$$

Question 12

Which of the following acids is correctly named?

Accepted Answer

HClO$$_4 is $$perchloric acid

Question 13

Which of the following is a diatomic molecule found naturally in the atmosphere?

Accepted Answer

O$$_2$$

Question 14

What is the charge on the sulfate ion?

Accepted Answer

$$-2$$

Question 15

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms of each element, while an empirical formula shows the lowest whole-number ratio.

Question 16

Which of the following is the correct name for $$N_2O_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 17

Which of the following statements about the periodic table is FALSE?

Accepted Answer

Nonmetals are found on the left side of the periodic table.

Question 18

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

Accepted Answer

$$Ca_3$$($$PO_4)_2$

Question 19

Which scientist is credited with the discovery of the nucleus?

Accepted Answer

Ernest Rutherford

Question 20

Which of the following is the correct name for $$CCl_4$$?

Accepted Answer

Carbon tetrachloride

Atoms, Molecules, and Ions: Foundations of Modern Chemistry

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