Astronomers observe huge bubbles of hot gas, some over a thousand light years across, in the Milky Way. What is their cause?
What will be an ideal response?
These huge bubbles, called "superbubbles," arise from many supernovae occurring close together in both space and time. The supernovae occur close together like this because stars tend to form in clusters and massive stars live for a relatively short time. When the massive stars in a cluster go supernova, they are still relatively close together and explode within a few hundred thousand years of each other (which is a short time compared to other galactic timescales).
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The quantum mechanical model of the hydrogen atom requires that if the orbital quantum number of the hydrogen atom is 7, there will be how many permitted orbital magnetic quantum numbers?
a. 6 b. 7 c. 14 d. 15 e. 49
A helium-filled weather balloon has a 0.50-m radius at liftoff where air pressure is 1.00 atm and the temperature is 290 K. When airborne, the temperature is 200 K, and its radius expands to 2.00 m. What is the pressure at the airborne location?
a. 0.0227 atm b. 0.172 atm c. 0.0108 atm d. 44.1 atm
Which of the following is not a derived quantity?
a. Volume b. Speed c. Mass d. Density
A narrow slit is illuminated with sodium yellow light of wavelength 589 nm. If the central maximum extends to ±30.0°, how wide is the slit?
a. 0.500 mm b. 2.20 × 10^-6 m c. 3.33 × 10^-5 m d. 1.18 mm e. 5.89 mm