Lesson test: The atomic hypothesis

1.[2p]
Which observations are explained by matter being made of discrete, identical units, but not by a continuum?

Select all that apply

A compound always contains the same elements in the same proportions by mass

Correct

The masses of oxygen combining with a fixed mass of nitrogen stand in the ratio 1:2:3:4:5

Correct

Mass is conserved through a chemical reaction

The answer is: A compound always contains the same elements in the same proportions by mass, The masses of oxygen combining with a fixed mass of nitrogen stand in the ratio 1:2:3:4:5, Gases react in simple whole-number ratios by volume

Gases react in simple whole-number ratios by volume

Correct

2.[2p]
The red oxide of copper is 88.8% copper by mass and the black oxide is 79.9%. Fixing the copper at one gram in each, what is the ratio of the oxygen masses, black to red?

CorrectNot quite: 2.00

3.[1p]
Dalton could not fix relative atomic masses from combining masses alone. What was the obstacle?

The balances of the period were not accurate enough

The answer is: One measurement had to determine two unknowns, the formula and the atomic mass ratio

One measurement had to determine two unknowns, the formula and the atomic mass ratio

Correct

He did not accept that mass is conserved

The answer is: One measurement had to determine two unknowns, the formula and the atomic mass ratio

Nobody had isolated pure enough samples

The answer is: One measurement had to determine two unknowns, the formula and the atomic mass ratio

4.[1p]
Dalton's rule of greatest simplicity led him to write water as HO, which is why his atomic weight for oxygen was wrong by a factor of two.

True

Correct

False

The answer is: True

5.[2p]
Two volumes of hydrogen and one of oxygen give two volumes of water vapour. What does Avogadro's hypothesis require in order to make this consistent?

That hydrogen and oxygen exist as diatomic molecules which split during reaction

Correct

That equal volumes of gas contain equal masses

The answer is: That hydrogen and oxygen exist as diatomic molecules which split during reaction

That water vapour is denser than the gases forming it

The answer is: That hydrogen and oxygen exist as diatomic molecules which split during reaction

That atoms of different elements have equal volumes

The answer is: That hydrogen and oxygen exist as diatomic molecules which split during reaction

1.[2p] Which observations are explained by matter being made of discrete, identical units, but not by a continuum?

2.[2p] The red oxide of copper is 88.8% copper by mass and the black oxide is 79.9%. Fixing the copper at one gram in each, what is the ratio of the oxygen masses, black to red?

3.[1p] Dalton could not fix relative atomic masses from combining masses alone. What was the obstacle?

4.[1p] Dalton's rule of greatest simplicity led him to write water as HO, which is why his atomic weight for oxygen was wrong by a factor of two.

5.[2p] Two volumes of hydrogen and one of oxygen give two volumes of water vapour. What does Avogadro's hypothesis require in order to make this consistent?

1.[2p]
Which observations are explained by matter being made of discrete, identical units, but not by a continuum?

2.[2p]
The red oxide of copper is 88.8% copper by mass and the black oxide is 79.9%. Fixing the copper at one gram in each, what is the ratio of the oxygen masses, black to red?

3.[1p]
Dalton could not fix relative atomic masses from combining masses alone. What was the obstacle?

4.[1p]
Dalton's rule of greatest simplicity led him to write water as HO, which is why his atomic weight for oxygen was wrong by a factor of two.

5.[2p]
Two volumes of hydrogen and one of oxygen give two volumes of water vapour. What does Avogadro's hypothesis require in order to make this consistent?