What is a planetary nebula?
What will be an ideal response?
A planetary nebula is a shell of gas that has been ejected during the evolution of a medium-mass star through a greatly increased stellar wind. The nebula is visible due to ionization from a central object (white dwarf) with a high surface temperature.
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Protostars can be observed in
A) the Crab Nebula. B) the Andromeda Galaxy. C) the Orion Nebula. D) our Solar System. E) the Helix Nebula.
A rock is projected from the edge of the top of a building with an initial velocity of 12.2 m/s at an angle of 53° above the horizontal. The rock strikes the ground a horizontal distance of 25 m from the base of the building. Assume that the ground is level and that the side of the building is vertical. How tall is the building?
a. 25.3 m b. 29.6 m c. 27.4 m d. 23.6 m e. 18.9 m
The following set of redox reactions takes place when iron is dipped in a solution of copper ions
Fe ? Fe+2 + 2e- Cu+2 + 2e- ? Cu Which of the following describes what is happening on the surface of the iron? A) The copper starts to plate out on iron. B) The iron rusts in the water. C) The iron starts to plate out on the copper. D) The iron corrodes the copper. E) none of the above
What is the MOST important role that proteins play in living organisms on Earth?
A) basic functioning of living organisms B) short-term energy storage C) information storage D) long-term energy storage and cell structure