13. An isotope of Hydrogen has A1 proton Bmore than oneproton Cno protons Dno el

Question

13. An isotope of Hydrogen has
A1 proton
Bmore than oneproton
Cno protons
Dno electrons 14. How bright is a star with a magnitude of +4.0 compared to astar with magnitude +5.0?
A2.5 timesbrighter
B2.5 timesfainter
C1.25 timesbrighter
D10 times brighter 15. Two stars have the same luminosity. As seen from Earth, onestar has an apparent brightness of four times the other. The dimmerstar
Ais eight timesfarther away than the brighter star.
Bis four times fartheraway than the brighter star.
Cis two times farther awaythan the brighter star.
Dis two times closer thanthe brighter star. 16. The spectral classification of a star is closely related toits
Aapparentbrightness.
Babsolutemagnitude.
Cluminosity.
Dsurfacetemperature. 17. The correct order of the spectral sequence from coolest tohottest stars is:
AO-B-A-F-G-K-M
BM-K-G-F-A-B-O
CM-K-F-G-B-A-O
DM-K-F-G-O-A-B 18. A star is observed to have a parallax of 0.1 arcseconds. Itsdistance is therefore
A1 pc.
B5 pc.
C10 pc.
D50 pc. 19. A B3 star is________ than a B4 star and________ than theSun.
Ahotter;hotter
Bhotter; cooler
Ccooler; hotter
Dcooler; cooler 20. Parallax of a nearby star is used to estimate its
Aapparentmagnitude.
Bphysical size ordiameter.
Cdistance fromEarth.
Dsurfacetemperature. 21. What is a star's luminosity?
AThe total energyemitted by the star per second, measured in watts.
BThe apparent magnitudethe star would have if it were located exactly 10 ly from theEarth.
CThe amount of energyreceived on one square meter of a planet's surface exactly 1 AUfrom the star, per second.
DThe apparent magnitudethe star would have if it were located exactly 10 pc from theEarth. 22. Absolute magnitude is defined as the apparent magnitude a starwould have if
Aall of the energyfrom the star were concentrated in the visual region.
Bthe star were located atexactly 10 pc from the Earth.
Cthe star were located atexactly 10 AU from the Earth.
Dthe star were located atexactly 10 ly from the Earth. 23. Apparent brightness can also be referred to as
APower
BEnergy
CFlux
DLuminosity 24. The spectral class of the star Enif is K2 while that of the Sunis G2. Which of the following conclusions can be drawn about Eniffrom this information?
AIt is hotter thanthe Sun.
BIt is cooler than theSun.
CIt is intrinsicallybrighter than the Sun.
DIt is intrinsicallyfainter than the Sun. 25. Which two physical parameters of stars are plotted on theHertzsprung-Russell diagram to show the systematics of a group ofstars (e.g., a cluster)?
ASurface temperatureand mass.
BLuminosity and surfacetemperature.
CLuminosity andradius.
DMass and apparentmagnitude.

Explanation / Answer

QuestionDetails: 18. A star is observed to have a parallax of 0.1 arcseconds.Its distance is therefore
A1 pc.
B5 pc.
C10 pc. Since 1 arc second equivalent to 1 parsec away (0.1 - > 10 pc)
D50 pc.

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