{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# exam 1 - Version 157 – Exam 1 – mcdevitt –(52365 1...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Version 157 – Exam 1 – mcdevitt – (52365) 1 This print-out should have 26 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. There are 25 regular exam questions each worth 8 points apiece for a total of 200 points (100 001 10.0 points A photon whose wavelength is 300 nm has energy 1. 1 . 982 × 10- 30 J. 2. 6 . 626 × 10- 28 J. 3. 6 . 022 × 10 23 J. 4. 4 . 528 × 10 44 J. 5. 6 . 626 × 10- 34 J. 6. 6 . 626 × 10- 19 J. correct Explanation: 002 10.0 points Radio station KLBJ broadcasts at a frequency of 93 . 7 × 10 6 s- 1 . Determine the length of the waves that corresponds to this frequency. 1. 2 × 10- 8 m 2. 93.7 m 3. 2 nm 4. 3.20 m correct 5. 3.20 nm Explanation: 003 10.0 points According to the results of Einstein’s photo- electric effect experiment 1. there is a threshold wavelength; at longer wavelengths, photoelectrons are pro- duced while at shorter wavelengths they are not. 2. there is a threshold temperature; at higher temperatures, photoelectrons are pro- duced while at lower temperatures they are not. 3. there is a threshold frequency; at higher frequency, photoelectrons are produced while at lower frequency they are not. correct 4. there is a threshold intensity; at higher intensity, photoelectrons are produced while at lower intensity they are not. Explanation: When electromagnetic radiation (light) of sufficient minimum energy strikes a metal cathode, electrons are knocked off its sur- face, travel to an anode, and form a current through a circuit. Two important observations were: 1) Electrons can be ejected only if the light is sufficiently energetic. Electron ejection is independent of time or intensity. The mini- mum energy varies by element. 2) The current increases with increasing intensity and is independent of color. Therefore, light is made up of photons, each having a particular amount of energy that can be transferred to an electron during a colli- sion. If the energy is equal to or greater than the amount needed to liberate the electron, it can escape to join the photoelectric current. Intensity is the number of photons hitting a surface per unit time. 004 10.0 points Write the ground-state electron configuration of Pb 2+ . 1. [Xe] 4 f 14 5 d 10 6 s 1 6 p 1 2. [Xe] 4 f 14 5 d 5 6 s 1 6 p 6 3. [Xe] 4 f 14 5 d 10 6 s 2 correct 4. [Xe] 4 f 14 5 d 5 6 s 2 6 p 5 5. [Xe] 4 f 14 5 d 10 6 p 2 Version 157 – Exam 1 – mcdevitt – (52365) 2 Explanation: Write the electron configuration for the atom and then adjust for the charge of the ion. The Aufbau order of electron filling is 1 s , 2 s , 2 p , 3 s , 3 p , 4 s , 3 d , 4 p , 5 s , 4 d , 5 p , 6 s , 4 f , 5 d , 6 p , etc ....
View Full Document

{[ snackBarMessage ]}

### Page1 / 8

exam 1 - Version 157 – Exam 1 – mcdevitt –(52365 1...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online