Deck 21: Stellar Remnants: Neutron Stars and Black Holes

Question 1

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

A)a nearby nova explosion in our galaxy
B)a brilliant auroral display covering the whole Earth
C)a supernova, visible in daylight
D)a bright binary star undergoing eclipse

Answer 1

C

Question 2

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

A)a supernova explosion in our galaxy, visible even in daylight
B)the passage of the planet Venus across the face of the Sun, a solar transit
C)the discovery of the planet Mercury
D)the total eclipse of the Sun in that year

Answer 2

A

Question 3

The Crab Nebula (M1) is:

A)a supernova remnant.
B)an H II region.
C)a newly forming star.
D)a black hole.

Answer 3

A

Question 4

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

A)x ray
B)visible
C)radio
D)a period of 1.337 s, corresponding to a very low wave frequency of 0.7479 Hz

Question 5

The first pulsar was discovered by:

A)the Hubble Space Telescope, soon after it was launched, in 1990.
B)Johannes Kepler, in 1604.
C)an English graduate student, Jocelyn Bell, in 1967.
D)the Astronomer Royal in Newton's time, Sir Edmund Halley, in 1606.

Question 6

The discovery of the Crab Pulsar, with a period of only 1/30 s, ruled out a number of possible explanations for pulsars. These included all of the following EXCEPT ONE. Which one was the exception?

A)eclipsing binaries
B)rapidly shifting dark dust clouds
C)variable stars
D)rotating white dwarfs

Question 7

The charged particles that emit the beams of electromagnetic radiation from a pulsar are believed to be:

A)iron and other nuclei pulled from the neutron star's crust by its intense magnetic fields.
B)plasma (ionized gas) spiraling onto the neutron star from a normal stellar companion.
C)electrons and hydrogen and helium nuclei from the neutron star's ionized atmosphere.
D)electron-positron pairs created by very strong electric fields near the neutron star's surface.

Question 8

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

A)Supernovae prior to 1967 did not produce pulsars.
B)It was a Type Ia supernova.
C)Any neutron star that may have formed is still hidden in debris and is not yet visible.
D)It was a Type II supernova.

Question 9

Astronomers originally rejected the idea that white dwarfs could rotate fast enough to be responsible for pulsar radiation. However, they soon accepted the idea that neutron stars could produce pulsar radiation. Why this difference?

A)The earlier rejection was mistaken. With sufficient evidence astronomers have come to believe that both white dwarfs and neutron stars can produce pulsar radiation.
B)There are two types of white dwarfs: those that produce Type Ia supernova and those that do not. The earlier rejection applied to the second type. It is now believed that the Ia supernova type white dwarfs, along with neutron stars, can produce pulsar radiation.
C)Neutron stars are smaller and even more dense than white dwarfs. Thus, they can rotate at tremendous rates without flying apart.
D)Neutron stars are held together by nuclear forces that are much stronger than the gravitational forces operating in white dwarfs. Thus, the surface of a neutron star can pulse in and out much more quickly than the surface of a white dwarf.

Question 10

The difference between a nova and an x-ray burst is that a nova involves:

A)an explosion on the surface of a neutron star, whereas an x-ray burst involves an explosion on the surface of a white dwarf.
B)an explosion on the surface of a neutron star, whereas an x-ray burst involves the complete collapse of a neutron star to form a black hole.
C)an explosion on the surface of a white dwarf, whereas an x-ray burst involves an explosion on the surface of a neutron star.
D)the complete explosive destruction of a white dwarf, whereas an x-ray burst involves an explosion on the surface of the white dwarf.

Question 11

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

A)1.4 M_ε
B)20 M_ε
C)about 100 M_ε
D)about 3 M_ε

Question 12

How long does a short gamma ray burst (short GRB) typically last?

A)about 2 ms
B)about 2 s
C)about 2 min
D)about 2 hours

Question 13

What event is now known to be a source of short GRBs?

A)the merger of two neutron stars
B)the merger of two white dwarf star
C)the merger of a white dwarf star and a neutron star
D)an explosion on the surface of a neutron star

Question 14

How much mass is lost when two 1-M_ε neutron stars merge?

A)less than 0.5%
B)about 1%
C)about 5%
D)more than 10%

Question 15

What happens to the mass ejected into space when two neutron stars merge?

A)A planetary nebula is created.
B)The mass falls back down onto the merged object.
C)A moon is eventually formed orbiting the merged object.
D)Large quantities of heavy elements such as gold and uranium are produced.

Question 16

How are large amounts of heavy elements, such as gold, silver, and uranium, known to be formed?

A)in the nova explosion on the surface of a white dwarf star
B)in the explosion that occurs on the surface of a neutron star
C)in the merger of two neutron stars
D)when a white dwarf star merges with a neutron star

Question 17

What is "special" about the special theory of relativity?

A)It deals only with objects that are at rest relative to one other.
B)It deals only with objects moving in a straight line at constant speed.
C)It deals only with motion at speeds significantly less than the speed of light.
D)It deals with motion at constant velocity and accelerated motion but excludes all other effects; in particular, it excludes gravity.

Question 18

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light)? Is this relativistic?

A)64% of c; yes
B)15% of c; no
C)97% of c; yes
D)c/1000; no

Question 19

You are flying your spacecraft on a parallel course with another spacecraft and at the same speed. You are both moving past Earth at an appreciable fraction of the speed of light. Which one of the following statements correctly describes the relationship between your clock and the clock in the other spacecraft?

A)You will see the clock in the other spacecraft running slow compared to yours.
B)You will see the clock in the other spacecraft running at the same rate as yours.
C)A person in the other spacecraft will see his own clock running slow compared to yours.
D)A person in the other spacecraft will see her own clock running fast compared to yours.

Question 20

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

A)300,000 km/s
B)300,014 km/s because your speed is added to that of the light and relativistic contraction has shortened your reference meter sticks
C)299,993 km/s because relativistic contraction has shortened all distances, including your reference meter sticks
D)300,007 km/s because your speed is added to that of the light

Question 21

A person is standing beside the open doorway of an empty barn. A pole of the same length as the barn is lying on the ground outside the barn. A second person picks up the pole and runs toward the barn at 90% of the speed of light, with the pole pointing toward the barn (a very athletic person!). How long does the pole appear to be to the person standing by the door, compared to the barn?

A)19% of the length of the barn
B)90% of the length of the barn
C)44% of the length of the barn
D)81% of the length of the barn

Question 22

A pole is lying on the ground outside a barn. The length of the pole is the same as the length of the barn. A person picks up the pole and runs toward the barn at 90% of the speed of light, with the pole pointing toward the barn (a very athletic person!). How long does the barn appear to be compared to the pole, as seen by the person running?

A)The barn appears to be 19% of the length of the pole.
B)The barn appears to be 5.3 times longer than the pole.
C)The barn appears to be 2.3 times longer than the pole.
D)The barn appears to be 44% of the length of the pole.

Question 23

At what speed would an object have to be traveling for its length to appear to a stationary observer to have decreased to 1/3 of its length when seen at rest? (c = speed of light)

A)0.11 c, or 11% of the speed of light
B)0.94 c, or 94% of the speed of light
C)0.33 c, or 1/3 c
D)0.89 c, or 89% of the speed of light

Question 24

Suppose that a particular kind of subatomic particle lives on average for exactly 1.0 microsecond (1.0 × 10^-6 s) before it decays, when this particle is created at rest in the laboratory. If a beam of such particles is created that travels at 97% of the speed of light as measured by a scientist standing beside the beam, what lifetime does the scientist measure for these particles?

A)4.1 microseconds
B)0.24 microsecond
C)16.9 microseconds
D)0.06 microsecond

Question 25

During a stop on Jupiter's satellite Europa to investigate a possible liquid ocean under the ice, you spot a spaceship passing Europa at 97% of the speed of light. While you see 2 s tick past on the spaceship's clock, how much time ticks by on your own clock?

A)8.2 s.
B)33.8 s.
C)0.12 s.
D)0.48 s.

Question 26

During a stop on Jupiter's satellite Europa to investigate a possible liquid ocean under the ice, you spot a spaceship passing Europa at 97% of the speed of light. A person on the spaceship sees 2 s tick past on your clock. How much time does this person see elapse on the clock on board her spaceship?

A)0.48 s
B)8.2 s
C)33.8 s
D)0.12 s

Question 27

To "spin up" the rotation of a neutron star, infalling material from the binary companion impacts the surface at half the speed of light. Suppose the infalling material includes radioactive particles with a half-life T₀ measured when the particle is at rest. What is the half-life of these particles measured by an observer on the neutron star?

A)0.5 T₀
B)0.87 T₀
C)1.15 T₀
D)2 T₀

Question 28

Einstein's principle of equivalence in his general theory of relativity asserts that:

A)the behavior of all types of atoms in a gravitational field is equivalent.
B)all objects are attracted toward all other objects in the universe by gravitational forces.
C)being at rest in a gravitational field is equivalent to being in an upwardly accelerated frame of reference in a gravity-free environment.
D)if person B is in a rapidly moving reference frame (moving at constant velocity), then person B will observe exactly the same effects for person A as person A observes for person

Question 29

Which of the following objects does NOT represent the endpoint of a star's evolutionary life?

A)black hole
B)neutron star
C)red giant
D)supernova

Question 30

In what way is the general theory of relativity more general (deals with more situations) than the special theory?

A)It includes accelerated motion but not gravitation.
B)It includes accelerated motion and gravitation.
C)It includes only constant, unaccelerated motion.
D)It includes only motion at the speed of light.

Question 31

How does a gravitational field affect the passage of time?

A)Gravity has no effect on the passage of time.
B)Clocks in a gravitational field run faster than clocks outside the field.
C)Gravity makes time stop.
D)Clocks in a gravitational field run slower than clocks outside the field.

Question 32

Suppose that, from a stationary spaceship, you identify a source of hydrogen (H_α) light on the surface of a planet that has a very strong gravitational field. When you observe an equivalent H_α light source on your spaceship, the wavelength is 656.3 nm. How long is the wavelength you measure when you look at the light source on the planet?

A)shorter than 656.3 nm
B)the same wavelength of 656.3 nm, but the frequency of the light appears lower
C)656.3 nm, the same as your light source, but the source appears very faint because the radiation has been weakened by the gravity field
D)longer than 656.3 nm

Question 33

Spectral lines detected from the surfaces of white dwarf stars are slightly redshifted with respect to the equivalent spectral absorption lines in the laboratory. Why is this?

A)The rapid rotation of these stars produces a redshift of light from atoms on their surfaces.
B)The extremely high temperature of the star surface affects the atomic energy levels and therefore the spectral lines produced by the atoms.
C)The steady shrinkage of white dwarf stars as they evolve is reflected in Doppler redshift of the surface spectrum.
D)Photons are gravitationally redshifted by the intense gravity field of the star.

Question 34

Two neutron stars form a close binary system and orbit each other rapidly. If we watch this motion from a position in the plane of the binary orbits, we would expect to see evidence of:

A)both a Doppler shift and a gravitational redshift.
B)a Doppler shift but not a gravitational redshift.
C)a gravitational redshift but not a Doppler shift.
D)neither a Doppler shift nor a gravitational redshift.

Question 35

What was Gravity Probe B designed to measure?

A)the speed of light
B)the curvature of spacetime around Earth
C)the precession of the perihelion of Mercury
D)the slowing of time in a gravitational field

Question 36

What is the correct explanation of the bending of a beam of light as it passes close to a massive object like the Sun?

A)The gravitational field interacts with the electromagnetic field of the photons to bend the light.
B)It is traveling across and must follow the curved space surrounding a massive object.
C)The gravitational field of the massive object changes the refractive index of the nearby space, leading to bending of the light.
D)The photons of light are attracted by the gravitational field of the massive object.

Question 37

What is the significance of the bending of a beam of light as it passes close to the Sun?

A)This behavior was predicted by Newton but not by Einstein.
B)This behavior was predicted by Einstein but not by Newton.
C)This behavior was predicted by both Newton and Einstein, but Einstein's theory gives the closer result.
D)This behavior was predicted by neither theory, and it remains a mystery.

Question 38

Why is the orbit of Mercury important from the standpoint of general relativity?

A)General relativity predicts that Mercury should move more slowly in its orbit than it does.
B)General relativity predicts the correct value for the advance of the perihelion of Mercury's orbit while Newtonian mechanics does not.
C)General relativity predicts the correct speed for Mercury in its orbit while Newtonian mechanics does not.
D)The inability to predict the advance of the perihelion of the orbit of Mercury is a significant failure for general relativity.

Question 39

The escape speed from a neutron star is:

A)less than the speed of light.
B)equal to the speed of light.
C)greater than the speed of light.
D)independent of the mass of the neutron star.

Question 40

Suppose that a neutron star of 2.8 M_ε is part of a binary star system in which the other star is a normal giant star. What would happen if 0.5 M_ε of material were transferred onto the neutron star from its companion?

A)The neutron star would collapse and become a black hole.
B)The increased gravitational force would transform the neutrons into quarks, and the neutron star would re-establish equilibrium as a quark star of smaller diameter.
C)The neutron degeneracy pressure inside the neutron star would increase to balance the increased gravitational force within the neutron star.
D)The neutron star would explode as a supernova.

Question 41

What would happen to the gravitational force on Earth if the Sun were to be replaced by a 1-M_ε black hole?

A)It would become extremely high, sufficient to pull Earth into it.
B)It would double in strength.
C)It would be much less, because the gravitational field of a black hole exists only very close to it.
D)It would remain as it is now.

Question 42

What is believed to be the maximum mass for a neutron star?

A)150 M_ε
B)12 M_ε
C)3 M_ε
D)1.4 M_ε

Question 43

The gravitational redshift of light leaving the surface of Sirius B is Δλ /λ = 3.0 × 10^-4. What velocity of Sirius B (relative to Earth) would be needed to produce an equivalent Doppler shift?

A)90 km/s away from Earth
B)90 km/s toward Earth
C)300 km/s away from Earth
D)300 km/s toward Earth

Question 44

Clock A sits on the surface of a neutron star, clock B sits on Earth's surface, and clock C rests beside me in space, far from any masses. The clocks are synchronized and all read 12:00 P.M. Ignore the delay caused by light travel time in this question. When clock C reads 1:00 P.M.:

A) clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with A earlier than B.
B) clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with B earlier than A.
C) clocks A and B will show times later than 1:00 P.M., with A earlier than B.
D) clocks A and B will show times later than 1:00 P.M., with B earlier than A.

Question 45

Who first predicted the existence of gravitational waves?

A)Isaac Newton, in 1710
B)Albert Einstein, in 1915
C)Edwin Hubble, in 1924
D)Stephen Hawking, in 1984

Question 46

The first two gravitational wave detectors were built in the United States. Where did the third detector come online in 2017?

A)Germany
B)South Africa
C)India
D)Italy

Question 47

Which of the following relativistic effects is measured when gravitational waves are observed?

A)change in time
B)change in length
C)change in mass
D)change in energy

Question 48

What is the approximate order of magnitude for the change in length in a detector arm caused by a passing gravitational wave?

A)10^-10 m
B)10^-20 m
C)10^-30 m
D)10^-40 m

Question 49

A gravitational wave is caused by:

A)accelerating masses.
B)increase in mass.
C)conversion of mass to energy.
D)conversion of energy to mass.

Question 50

All the following events are likely to generate observable gravitational waves EXCEPT ONE. Which one is the exception?

A)merger to two neutron stars
B)supernova explosion of very massive star
C)merger of two black holes
D)1-M ? star falling into black hole

Question 51

In the event observed by LIGO on September 14, 2015, two black holes with a combined mass of 65 M_ε merged to form a black hole with 63 M_ε. What happened to the difference in mass?

A)It was converted almost instantly into gravitational wave energy.
B)It was converted into smaller particles like neutrinos.
C)It formed an accretion disk around the merged black hole.
D)It was converted into different wavelengths of visible light.

Question 52

A black hole is believed to form:

A)when two solar mass stars collide.
B)by the condensation of a dust cloud that is too cold to form a star.
C)by the gravitational collapse of a planetary nebula.
D)at the end of the evolution of a very massive star.

Question 53

All black hole candidates observed so far are:

A)eclipsing binaries in which the light is totally extinguished periodically.
B)dark areas surrounded by light from background stars.
C)x-ray sources in spectroscopic binary systems.
D)"attractors" toward which objects within a large volume of space are accelerating.

Question 54

As light moves outward from the vicinity of a black hole:

A)its energy increases.
B)its energy decreases.
C)its energy remains the same.
D)the photons are stopped and remain suspended in space.

Question 55

What is believed to be the mass of the black hole candidate Cygnus X-1?

A)30 M_ε
B)1 billion M_ε
C)15 M_ε
D)1 M_ε

Question 56

The mass of Cygnus X-1 is estimated to be 14.8 M_ε. How was this determined?

A)measurement of the gravitational redshift
B)use of Kepler's third law
C)measurement of the Doppler shift of the binary system, of which it is a part
D)visual measurement of the "wobble" in the binary system

Question 57

One of the best candidates for a black hole in a binary star system at the present time, based on the accuracy of measuring its mass, is:

A)V404 Cygni.
B)LMC X-3.
C)Cygnus X-1.
D)HDE 226868.

Question 58

The x-ray source Cygnus X-1 is a black hole candidate located in a binary star system. The x-ray source is believed to occupy a volume smaller than Earth. This size is deduced from:

A)its luminosity and spectral class.
B)the shortness of its orbital period.
C)the short time period of the rapid flickering in its x-ray brightness.
D)its distance from Earth and the angle it subtends in the sky.

Question 59

If an astronomical source of electromagnetic radiation is observed to flicker, with intensity changes in as short a time as 1/30 s, how large is the emitting region?

A)10,000 km, a little smaller than Earth
B)1/30 ly
C)9 × 10⁶ km, about 6 times the size of the Sun
D)10,000 m, about the size of a small city or town

Question 60

Which of the following would NOT be considered a possible mechanism for the production of a black hole with a mass of a few solar masses?

A)coalescence of a binary pair of dead stars that spiral into one another after losing rotational energy as gravitational radiation
B)slow gravitational condensation of a massive gas cloud directly into a black hole
C)accretion of mass onto a white dwarf or neutron star from the companion star in a binary star system
D)one member of a binary star exploding as a Type II supernova, leaving a black hole

Question 61

A flickering signal is received from a source the size of the Sun. What frequencies are possible for this flicker?

A)any frequency at all depending on the source mechanism
B)0.21 cycles per second or more
C)0.21 cycles per second or less
D)0.42 cycles per second or more

Question 62

Gamma-ray bursters are:

A)ordinary Type Ic supernovae.
B)ordinary Type II supernovae.
C)Type Ic supernovae with jets funneling most of the radiation in two narrow directions.
D)Type II supernovae with jets funneling most of the radiation in two narrow directions.

Question 63

What is the duration of a gamma-ray burst?

A)as short as one-hundredth of a second, indicating a source smaller than Earth
B)several days, indicating a size much smaller than the distance from Earth to the nearest star beyond the Sun
C)up to about 1 day, indicating a source several times the size of our solar system
D)several hours, indicating a source size about equal to the diameter of Uranus's orbit

Question 64

What property of gamma-ray bursters indicates that they are located at large ("cosmological") distances from Earth?

A)their positions correlating with galaxies known to be at large distances
B)the small apparent sizes of the objects producing the bursts
C)highly redshifted emission lines from the burster's nucleus
D)the faintness of the bursts

Question 65

What is a collapsar?

A)the name given to any massive star that collapses to form a white dwarf, neutron star, or black hole
B)a system in which a very massive star collapses to form a black hole surrounded by an accretion disk and jets that beam intense gamma-ray radiation
C)any gamma-ray burster
D)the bright flash of light that signals the merger of a black hole and its companion star

Question 66

A typical galaxy has a mass of 10¹¹ M_ε. If 1% of this mass collects at the center of the galaxy to become a nonrotating black hole, what will be its Schwarzschild radius?

A)20 au
B)20,000 au
C)20 ly
D)20 pc

Question 67

What is believed to be the mass of the black hole candidate at the center of the galaxy NGC 4261?

A)120 M_ε
B)120,000 M_ε ​
C)1.2 million M_ε
D)1.2 billion M_ε

Question 68

The mass of the candidate black hole at the center of the galaxy NGC 4261 was estimated from the:

A)application of Kepler's laws to the orbital speed of objects close to this center.
B)intensity of x rays from it and the speed at which the x rays flicker.
C)amount of mass that is disappearing into it per year.
D)periodic shift in the wavelengths of spectral lines from a companion object around which the black hole is orbiting.

Question 69

What is the relationship between the size of black hole and its density?

A)Larger black holes have greater densities than smaller black holes.
B)Smaller black holes have greater densities than larger black holes.
C)All black holes have approximately the same density.
D)There is no relationship between size and density of a black hole.

Question 70

We believe the bright central object in the galaxy NGC 4261 is only about the size of our solar system. What evidence do we have for this size estimate?

A)This is a direct measurement from the image seen with the HST.
B)We have measured and compared the Doppler shifts for material on the near and far sides of the object.
C)Radiation from this central object fluctuates, and the light can only travel this distance (the size of the solar system) during a typical fluctuation.
D)We estimate the mass of this central object to be 1.2 billion M ? , and this is the Schwarzschild radius that gives nuclear matter density for this mass.

Question 71

Theoretically, the mass of a black hole:

A)must be at least 10⁶ M_ε.
B)must be at least 10 M_ε.
C)must be at least 1.4 M_ε.
D)can have any mass.

Question 72

Theoretically, a black hole can have:

A)any mass greater than 0.04 M_ε.
B)any mass greater than 3 M_ε.
C)any mass greater than 14.8 M_ε.
D)any mass.

Question 73

What is the current status of primordial black holes?

A)Primordial black holes have been created in the laboratory but never observed in nature.
B)Primordial black holes have been observed in supernova remnants.
C)No primordial black holes have been observed.
D)Primordial black holes have been found virtually everywhere in the universe.

Question 74

Which of the following was discovered first?

A)Supermassive black hole
B)Stellar mass black hole
C)Primordial black hole
D)Intermediate mass black hole

Question 75

Far outside a black hole, space seems flat and times seems independent of space. But, inside the event horizon of a black hole, it would be readily apparent that:

A)time flows backward.
B)time and space are interchanged, each replacing the other.
C)time and space are interdependent, each depending on the other.
D)neither time nor space exists.

Question 76

How does the attractive force you feel compare if you are just outside the event horizon of a massive black hole or of a relatively small black hole?

A)Because of its larger mass, the massive black hole will exert the larger force.
B)As the mass of the black hole increases, the Schwarzschild radius increases linearly but the gravitational attraction decreases as 1/r². Thus, the larger black hole exerts the smaller force.
C)As the mass of the black hole increases, the Schwarzschild radius increases linearly but the gravitational attraction decreases as 1/r². Thus, the larger black hole exerts the larger force.
D)All black holes exert a large but equal force on an object just outside the event horizon.

Question 77

The escape velocity of matter from the center of a black hole whose mass is 3 M_ε is:

A)quite small.
B)greater than the speed of light.
C)exactly equal to the speed of light.
D)about half the speed of light.

Question 78

The only parts of a nonrotating black hole that are necessary for its complete description are:

A)the escape velocity of matter and the diameter of its core.
B)its center, or singularity, and its "surface," or event horizon.
C)the gravitational field and the curvature of space at its center.
D)its semimajor axis and its orbital eccentricity.

Question 79

The Schwarzschild radius of a black hole is the distance from the singularity (center) to the:

A)point where the gravitational field becomes zero.
B)event horizon, from which light cannot escape.
C)outside radius of the massive solid body forming the black hole.
D)accretion disk, from which x rays originate and from which light can still escape.

Question 80

The radius of the event horizon of a black hole, the Schwarzschild radius:

A)is constant, because the general theory of relativity states that the size of a black hole is independent of its mass.
B)is smaller the more massive the black hole, because the matter will be more condensed.
C)will not depend on its mass but will depend on the material from which it was formed, a "hydrogen" black hole being smaller than an "iron" black hole.
D)is larger, the more massive the black hole.