Q: According to the law of conservation of mass, which equation correctly represents the relationship between the mass of reactants and products in a chemical reaction?

$$\text{mass of reactants} = \text{mass of products}$$

Q: Which equation correctly calculates the average atomic mass 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 scientist provided the first convincing evidence supporting the atomic theory proposed by Leucippus and Democritus?

Accepted Answer

John Dalton

Question 2

According to the law of conservation of mass, which equation correctly represents the relationship between the mass of reactants and products in a chemical reaction?

Accepted Answer

$$	ext{mass of reactants} = 	ext{mass of products}$$

Question 3

Which law states that all samples of a given compound have the same proportions of their constituent elements?

Accepted Answer

Law of definite proportions

Question 4

A compound contains 16.0 g of oxygen and 2.0 g of hydrogen. What is the mass ratio of oxygen to hydrogen in this compound?

Accepted Answer

$$8:1$$

Question 5

Which experiment led to the discovery of the electron and its charge-to-mass ratio?

Accepted Answer

Thomson's cathode ray tube experiment

Question 6

What is the charge of a neutron?

Accepted Answer

0

Question 7

Which statement best describes isotopes?

Accepted Answer

Isotopes have the same atomic number but different mass numbers.

Question 8

If an atom has 11 protons, 12 neutrons, and 10 electrons, what is its charge?

Accepted Answer

+1

Question 9

Which group in the periodic table contains elements that are mostly unreactive?

Accepted Answer

Noble gases

Question 10

Which property is NOT characteristic of metals?

Accepted Answer

Gain electrons during chemical changes

Question 11

Which element is a liquid at room temperature?

Accepted Answer

Bromine

Question 12

Which equation correctly calculates the average atomic mass 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 13

How many atoms are in 2 moles of sodium?

Accepted Answer

$$1.204 	imes 10$$^{24}$$

Question 14

Which scientist is credited with the discovery of radioactivity?

Accepted Answer

Henri Becquerel

Question 15

Which type of ion is formed when an atom loses electrons?

Accepted Answer

Cation

Question 16

A sample contains 75.0 g of mercury (Hg). If the molar mass of Hg is 200.59 g/mol, how many moles of Hg are present?

Accepted Answer

$$0.374$$ mol

Question 17

Which element did Mendeleev predict before it was discovered, later named germanium?

Accepted Answer

Eka-silicon

Question 18

Which statement about the periodic table is correct?

Accepted Answer

Elements are arranged by increasing atomic number.

Question 19

Which group contains elements that are very reactive nonmetals?

Accepted Answer

Group 7A

Question 20

Which property is typical of metalloids?

Accepted Answer

Intermediate electrical conductivity

Atoms and Elements: Foundations of Modern Atomic Theory

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