SOLVED

91.Why might it be difficult for Earth-like planets to form around Sun-like stars in the outer parts of the disk of our galaxy? A)there would be insufficient amounts of heavy elements B)the stars would be packed together too densely for planets to be stable C)any stars would be sucked into the central supermassive black hole D)there would be too much harmful radiation 92.If our solar system hadn’t formed with a Jupiter-sized planet, A)the Sun would have been more massive, with a lifetime too short for life to evolve B)the Earth would have never formed C)the rate of impacts on the Earth may have been much higher, possibly preventing the appearance of life D)the rate of impacts on the Earth may have been much lower, enabling the appearance of life much earlier 93.The Hertzprung–Russell diagram is a plot of A)radial velocity against distance B)apparent brightness against time C)luminosity against distance D)luminosity against surface temperature 94.On the Hertzprung–Russell diagram, most stars are found A)on the main sequence B)in the red giant region C)in the white dwarf region D)in the supergiant region 95.All stars on the main sequence A)are in the process of forming B)are mature stars that are fusing hydrogen into helium in their cores C)are dead stars D)have exhausted their nuclear fuel and are in the process of dying 96.At the upper right of the Hertzprung–Russell diagram we find A)red giant stars B)red supergiant stars C)white dwarfs D)main sequence stars 97.At the top of the Hertzprung–Russell diagram we find A)red giant stars B)white dwarfs C)supergiant stars D)main sequence stars 98.At the lower left of the Hertzprung–Russell diagram we find A)supergiant stars B)red giant stars C)white dwarfs D)main sequence stars 99.Red giants A)are mature stars that are fusing hydrogen into helium in their cores B)are dead stars C)have exhausted their nuclear fuel and are in the process of dying D)are in the process of forming 100.White dwarfs A)are dead stars B)are in the process of forming C)are mature stars that are fusing hydrogen into helium in their cores D)have exhausted their nuclear fuel and are in the process of dying