**Q1: **

A gas of helium atoms at a temperature of 273 K is in a cubical container with a side length of 25.000 cm.

What is the minimum uncertainty in the momentum components of helium atoms?

- A N⋅s
- B N⋅s
- C N⋅s
- D N⋅s
- E N⋅s

What is the minimum uncertainty in the velocity components of the helium atoms?

- A m/s
- B m/s
- C m/s
- D m/s
- E m/s

What is the ratio of the minimum uncertainty in the velocity components of helium atoms to the mean speed of the atoms?

- A
- B
- C
- D
- E

**Q2: **

An unstable elementary particle has a rest energy of 80.41 GeV and an uncertainty in rest energy of 2.06 GeV. What is the minimum lifetime of this particle?

- A s
- B s
- C s
- D s
- E s

**Q3: **

Use the Heisenberg uncertainty principle to calculate the uncertainty in energy for a corresponding time interval of s.

- A GeV
- B GeV
- C GeV
- D GeV
- E GeV

**Q4: **

Measurements indicate that an atom remains in an excited state for an average time of 50.0 ns before making a transition to the ground state with the simultaneous emission of a 2.10-eV photon.

What is the minimum uncertainty in the frequency of the emitted photon?

What fraction of the emitted photon’s average frequency is the minimum uncertainty in its frequency?

- A
- B
- C
- D
- E