(Section 1.4: #40:) The half-life of radioactive cobalt is 5.27 years. Suppose that a nuclear accident has left the level of cobalt radiation in a certain region at 100 times the level acceptable for human habitation. How long will it be until the region is again habitable? (Ignore the probable presence of other radioactive isotopes.)

There is a single path for electrons. the current decreases when additional resistors are added. the current will be the same in each resistor. these statements best describe a(n) circuit.

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains

What are the first two quantum numbers for the electrons located in subshell 4d? what are the first three quantum numbers for the electrons located in subshell 2s? how many electrons can be held in a sublevel l = 3? how many electrons can be held in the energy level n = 4? how many electrons in an atom can share the quantum numbers n = 4 and l = 3?