A scientist claims that all red main-sequence stars are 1 billion years old. Which of the following, if true, would prove that this claim is false?
A) The discovery of a red main-sequence star in a star cluster where the main sequence turnoff is about that of the Sun
B) The discovery of a red main-sequence star in a star cluster where all the other stars are red giants or red supergiants
C) Stellar evolution theory predicts that the main-sequence lifetime of red stars can be as long as 100 billion years.
D) The minimum lifespan of a red main-sequence star is estimated to be 10 billion years.
A
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Consider a uniform horizontal electric field of 50 N/C directed toward the east. If the electric potential at a given point in the field is 80 V, what is the potential at a point 1.0 m directly east of the point?
A) 30 V B) 90 V C) 15 V D) 130 V
The diameter of the average nucleus is about ______________ m
Fill in the blank(s) with correct word
The angle that an incident light ray makes with the surface normal is
A. smaller than the angle that the reflected ray makes with the normal B. the same size as the angle that the reflected ray makes with the normal C. greater than the angle that the reflected ray makes with the normal
Which of these will penetrate into lead?
A) alpha particle B) beta particle C) gamma ray. D) all of the above