What is a planetary nebula?Group of answer choicesthe expanding shell of gas that is left when a white dwarf explodes as a supernovathe cloud of gas and dust from which protostars formthe expanding shell of gas that is blown off by a star when it becomes a white dwarfa disk of gas surrounding a protostar that may form

Which of these is true of planetary nebulae?Group of answer choicesThey are rings of material around protostars that will accrete into planets in time.They are ejected envelopes surrounding a highly evolved low mass star.They are the material which causes the eclipses in eclipsing binary systems.They are expelled by the most massive stars in their final stages before supernova.They are the envelopes that form when blue stragglers merge.

A nebula is a cloud of gas and dust in space.  What is the most common type of gas found inside a nebula?HydrogenHeliumKryptonOxygen2Gravity due to the mass contained within a nebula can cause it to collapse in on itself.  In what way does the temperature of the nebula change as this happens?It increasesIt stays the sameIt decreasesIt is impossible to say without knowing the exact composition of the nebula3Which element is formed when two hydrogen nuclei fuse together?IronCarbonOxygenHelium4Which of the following can be said of a main sequence star such as the Sun?The force due to gravity at a given point within it is greater than the force due to gas pressureThe force due to gravity at a given point within it is equal to the force due to gas pressureIt is impossible to say how the force due to gravity at a given point within the star compares to the force due to gas pressure without knowing the exact composition of the starThe force due to gravity at a given point within it is less than the force due to gas pressure5What will happen to the Sun immediately after all of the hydrogen in its core has been used up?It will turn into a black dwarfIt will turn into a supernovaIt will turn into a red supergiantIt will turn into a red giant6All of the nuclei in the Universe which are heavier than a particular element were produced in supernovae.  Which element is this?IronUraniumLeadCarbon

How do solar nebulae and planetary nebulae differ? aPlanetary nebulae result from the explosions of massive stars, whereas solar nebulae are ejected by smaller stars. bSolar nebulae are clouds of gas and dust where planets, stars, and other celestial bodies form, whereas planetary nebulae are ejected by dying stars. cPlanetary nebulae result from the explosions of planets, whereas solar nebulae result from the explosions of stars. dPlanetary nebulae result in the formation of planets, whereas solar nebulae result in the formation of stars.

First Stage: The star starts out as diffused clouds of gas and dust drifting through space. One of these clouds is called a ...*1 pointPlanetary nebulaMolecular cloudProtostarAccretion DisSupernovaStar

Because of the previous question, the star begins to shrink and the outer layers are cast off forming a...*1 pointsupernovaplanetary nebulaaccretion diskmolecular cloud