$$ \frac{23.1}{0.408} = 56.6 \text{ g} $$

$$ 17.7 + 11.9 = 29.6 \text{ g} $$

$$ \frac{4.0}{10.0} \times 100 = 40\% $$

Question 1

Which statement best describes Dalton's Atomic Theory as proposed in 1808?

Accepted Answer

Atoms of a given element are identical in mass and properties, and chemical reactions only rearrange how atoms are bonded.

Question 2

Which experiment provided direct evidence for the existence of the electron?

Accepted Answer

JJ Thomson's Cathode Ray Tube Experiment

Question 3

According to the Law of Definite Proportions, which statement is true?

Accepted Answer

All samples of a compound have the same proportions of their constituent elements.

Question 4

Which model of the atom was described as a 'chocolate chip cookie'?

Accepted Answer

Thomson's Plum Pudding Model

Question 5

A sample of water contains 23.1 g of oxygen. How many grams of water are present if water contains 40.8% oxygen by mass?

Accepted Answer

$$ \frac{23.1}{0.408} = 56.6 	ext{ g} $$

Question 6

Which law states that in a chemical reaction, matter is neither created nor destroyed?

Accepted Answer

Law of Conservation of Mass

Question 7

If 17.7 g of Na(s) reacts with 11.9 g Cl$$_2(g$$), how many grams of NaCl(s) are formed?

Accepted Answer

$$ 17.7 + 11.9 = 29.6 	ext{ g} $$

Question 8

Which scientist's experiment led to the discovery that atoms have a small, dense nucleus?

Accepted Answer

Ernest Rutherford

Question 9

Which statement about isotopes is correct?

Accepted Answer

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

Question 10

A 10.0 g sample of calcite contains 4.0 g of calcium. What is the percent by mass of calcium in calcite?

Accepted Answer

$$ \frac{4.0}{10.0} 	imes 100 = 40\% $$

Question 11

Which concept explains why carbon and oxygen can combine to form both CO and CO$$_2$$?

Accepted Answer

Law of Multiple Proportions

Question 12

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 13

Which experiment measured the charge of the electron?

Accepted Answer

Millikan Oil Drop Experiment

Question 14

Which statement about ions is correct?

Accepted Answer

An ion is an atom that has gained or lost electrons.

Question 15

Which scientist's work provided evidence for the atomic nature of matter through the observation of Brownian motion?

Accepted Answer

Albert Einstein

Question 16

If a sample contains $$ 6.022 	imes 10$$^{23}$$ $$ atoms, how many moles of atoms are present?

Accepted Answer

$$ 1 $$ mole

Question 17

Which statement about the periodic table is correct?

Accepted Answer

Elements are grouped by similar chemical properties.

Question 18

Which of the following best describes Rutherford's Nuclear Model of the atom?

Accepted Answer

Atoms consist of a positively charged nucleus surrounded by electrons.

Question 19

Which law explains why the mass of reactants equals the mass of products in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Question 20

Which of the following is a real-world application of the Law of Definite Proportions?

Accepted Answer

Water from different sources always contains hydrogen and oxygen in a 2:1 ratio by atom.

Atoms and Elements: Foundations of Atomic Theory

Guida di studio - Domande di pratica