During our "field trip" to the Dept. of Physics cloud chamber, you should have observed the formation of tracks. If you didn't, please go back and have a look since if you are by yourself you'll have plenty of room to see. Which of the following is/are potential candidates for the particles that caused the tracks?
Here you get only one single try, + marks for every correct, minus marks for every incorrect.
Select all that apply:
a. gamma rayscross out
b. electronscross out
c. protonscross out
d. neutronscross out
e. antineutronscross out
Two liters of ammonia (NH3) are made to react with 2 liters of oxygen (O2) to produce nitrous oxide (N2O) and water vapor. How many liters of nitrogen dioxide and water vapor are produced?
Penalty factor 25%
Select one:
a. one liter of nitrous oxide and one liter of water.cross out
b. one liter of nitrous oxide and two liters of water.cross out
c. one liter of nitrous oxide and three liters of water.cross out
d. two liters of nitrous oxide and one liter of water.cross out
e. three liters of nitrous oxide and one liter of water.
The presence of >1 proton (mass 1.67 x 10-27 kg, radius ~0.88 fm) in a nucleus unequivocally implies:
Penalty factor 25%
Select one:
a. that the nucleus must be held together by proton-proton or proton-neutron gravitation.cross out
b. That the electromagnetic force is always attractive in the nucleus.cross out
c. that negatively charged nucleons must also exist.cross out
d. that the electrons must help to stabilize the nucleus.cross out
e. That there must exist another force that's stronger than the electromagnetic force and is not gravity.
Lithium has two stable isotopes. One of them has three neutrons, and the other has four. Using the known atomic weight of lithium (6.941 amu), calculate the percentage of natural lithium that is lithium-6.
By the way, I'm perfectly aware that the percentages are given in the link above. But the main purpose is to understand what the atomic weights mean and to do a simple calculation on that basis. Just to avoid temptation though, I'll ask you to please give the result to a four-digit accuracy (like the weight given above).
To do this properly, we cannot assume that the atomic weights of Li-6 and Li-7 are exactly 6 and 7, surprisingly enough. We will find out more about why that is later (it's nothing to do with isotope ratios as these are the pure isotopes). The actual weights of the two isotopes are 6.015 and 7.016 amu, respectively, as listed here.