Calculate the mass of oxygen (in mg) dissolved in a 3.14 l bucket of water exposed to a pressure of 1.02 atm of air. assume the mole fraction of oxygen in air to be 0.21 and the henry's law constant for oxygen in water at this temperature to be 1.4 × 10-3 m/atm o2. (enter your value using three significant figures.)

Which statement best describes who the period and frequency of electromagnetic was change between gamma rays and microwaves? a) the period and frequency stay the same. b) the period increases and the frequency decreases. c) the period decreases and the frequency increases. d) the period increases and the frequency increases.

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies. molten iron has a density of 7.0g/cm cubed. in its solid state, iron has a density of 8.0g/cm cubed.

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.