Quiz 2.3 - Protons and neutrons

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This quiz has 7 questions. Click Submit at the end to mark it. No personal data is collected.

1. Why did it seem reasonable that the atomic nucleus might be composed of smaller parts? Choose two. *

1 point

Scientists could see them with powerful microscopes

If the atom was made of smaller parts then maybe the nucleus was, too

Different nuclei had different masses and charges, so maybe that was because they were built up from smaller pieces

Required

2. How was the proton discovered? *

1 point

When an alpha particle turned into a hydrogen nucleus

When a hydrogen nucleus was absorbed by a nitrogen nucleus

When an alpha particle seemed to knock a hydrogen nucleus out of a nitrogen nucleus

3. Why did it seem that the nucleus should be made up of other neutral particles as well as protons? *

1 point

The nucleus had to be neutral overall, and protons are positive

The protons didn't account for all the mass of a nucleus, and whatever else was there couldn't have any electric charge

Protons were different sizes so they didn't always add up to the measured mass of a nucleus

4. Why would neutrons be difficult to detect? *

1 point

Neutrons had no electric charge so wouldn't be deviated by a nucleus, which was positively charged

Neutrons were travelling too fast to be caught on film

Neutrons would all be absorbed by any nucleus they hit

5. Why was it strange that protons were given off in Irene and Frederick Joliot-Curie's experiment? *

1 point

Because alpha particles should have gone straight throught the beryllium metal

Because paraffin wax doesn't contain protons

Because the alpha particles didn't hit the paraffin wax directly, so it must be something given off by the beryllium

6. True or False? James Chadwick guessed that the alpha particles were knocking out neutrons from the beryllium nuclei, which in turn were knocking out protons from the paraffin wax. *

1 point

True

False

7. How did Chadwick measure the mass of a neutron to be slightly bigger than a proton? *

1 point

He took photographs of the neutrons as they passed

He could measure the speed of the protons and use that to calculate the speed of the neutrons

He used a special balance to compare the two masses

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