Aportion of the mesosphere and thermosphere known for its ability to "bounce" radio signals is the
a. exosphere
b. ionosphere
c. stratosphere
d. troposphere

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.

How many electrons in an atom could have these sets of quantum numbers? =3n=3 electronselectrons =4,ℓ=2n=4,ℓ=2 electronselectrons =6,ℓ=ℓ=−1n=6,ℓ=2,mℓ=−1

Awelder using a tank of volume 7.50×10^-2 m^3 fills it with oxygen (with a molar mass of 32.0 g/mol ) at a gauge pressure of 3.30×10^5 pa and temperature of 37.1 ∘c. the tank has a small leak, and in time some of the oxygen leaks out. on a day when the temperature is 23.1 ∘c, the gauge pressure of the oxygen in the tank is 2.00×10^5 pa . a) find the initial mass of oxygen. b) find the mass of oxygen that has leaked out.