Question 1

The age of the solar system is believed to be approximately 4.6 billion years based on the data from
A) samples of lunar rocks.
B) samples of Earth rocks.
C) samples of meteorites.
D) all of the above.
E) none of the above.

Accepted Answer

The age of the solar system is estimated to be about 4.6 billion years based on radiometric dating of samples from lunar rocks, Earth rocks, and meteorites. All these sources provide consistent evidence for the age of the solar system.

Question 2

The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because
A) the solar nebula from which the planets formed had a disk-like structure.
B) the bipolar flow from the young sun cleared all material out of the nebula except that in the disk.
C) Jupiter's gravity was great enough to pull all of the other planets to the plane of its orbit.
D) the Milky Way Galaxy from which the planets condensed has a disk-like structure

Accepted Answer

The most widely accepted explanation for the disk-like structure of the solar system is that it is a result of the solar nebula from which the planets formed having a disk-like structure. As the nebula collapsed, it began to rotate faster and faster, and conservation of angular momentum caused it to flatten into a disk. The planets then formed from this flattened disk of material.

Question 3

Protoplanets of the Jovian planets could have grown very hot from
A) heat for the sun.
B) radioactivity of light elements such as hydrogen and helium.
C) the infall of material at high velocity.
D) tidal forces due to the sun.
E) collisions with large planetesimals.

Accepted Answer

The infall of material at high velocity would generate a large amount of kinetic energy, which would convert to heat as the protoplanet grows. This process is known as accretion heating. The other choices may contribute to heating as well, but not to the same extent as the infall of material.

Question 4

The uncompressed density of a planet in our solar system
A) is greatest for the Jovian planets.
B) is greatest for the planets closest to the sun.
C) is greatest for the planets furthest from the sun.
D) is greatest for the planets with the largest mass.
E) is greatest of the planet with the largest radius.

Accepted Answer

The answer of The uncompressed density of a planet in...

Question 5

The large planetesimals would have grown faster than the smaller planetesimals because
A) they were moving faster in their orbits than the smaller planetesimals.
B) their stronger gravity would pull in more material.
C) there was more material located near them that could be accreted.
D) the smaller planetesimals were covered by a layer of material that was lost during collisions.
E) all of the above.

Accepted Answer

The stronger gravity of the larger planetesimals would pull in more material, causing them to grow faster than the smaller planetesimals. Choices A, C, and D are not necessarily true for all cases and do not explain why the larger planetesimals would grow faster.

Question 6

The most important effect in clearing the solar nebula of gas and dust was
A) impacts by planetesimals.
B) the solar wind.
C) the sun's magnetic field.
D) the asteroid belt.
E) radiation pressure.

Accepted Answer

The answer of The most important effect in clearing the...

Question 7

If the terrestrial planets were formed by homogeneous accretion, then
A) they were initially molten forming an iron core first, then they accreted a silicate crust later.
B) they were initially molten forming a silicate core first, then they accreted an iron crust later.
C) they were initially collections of solid particles which melted then differentiated into a high-density iron metal core and low-density silicate crust.
D) they were initially collections of solid particles which melted then differentiated into a high-density silicate core and low-density iron metal crust.

Accepted Answer

Homogeneous accretion suggests that terrestrial planets started as collections of solid particles. These particles then melted due to heat from impacts, radioactive decay, or gravitational compression, leading to differentiation based on density. This process resulted in the formation of a high-density iron metal core surrounded by a low-density silicate crust.

Question 8

Which one of the following objects is most like the planetesimals that formed in the solar nebula?
A) asteroids
B) Earth
C) Saturn
D) Venus
E) the sun

Accepted Answer

Planetesimals are small, rocky or icy bodies that formed during the early stages of the solar system's formation. Asteroids are also small, rocky bodies that formed from planetesimals, making them the most similar to the original planetesimals. Earth, Saturn, Venus, and the sun are all much larger and formed later in the solar system's evolution.

Question 9

The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system?
A) common direction of rotation of the planets
B) common direction of revolution of the planets
C) the formation of hydrogen atoms in the solar system from subatomic particles
D) the density of the Jovian planets

Accepted Answer

The solar nebula theory explains the formation of the solar system by the collapse of a rotating cloud of dust and gas. It can explain the common direction of rotation and revolution of the planets as well as the density of the Jovian planets. However, it cannot explain the formation of hydrogen atoms in the solar system from subatomic particles, as this is a process that occurred in the early universe before the formation of the solar system.

Question 10

Accretion among the grains in the solar nebula would have been aided by
A) static electricity.
B) gravity.
C) high-velocity collisions.
D) all of the above.
E) none of the above.

Accepted Answer

The answer of Accretion among the grains in the solar...

Question 11

What observation made of other stars seems to suggest the solar nebula theory is correct?
A) Stars are found to exist more often in binaries than by themselves.
B) Protostars are seen to radiate much of their light at infrared wavelengths.
C) Nearby stars tend to be low-mass red dwarfs.
D) Young stars are found to have hot disks that surround them.

Accepted Answer

The observation of young stars having hot disks that surround them supports the solar nebula theory which suggests that a disk of gas and dust surrounded the young sun and eventually formed the planets.

Question 12

The diagram below illustrates the radioactive decay of Potassium (⁴⁰K), which has a half-life of 1.3 billion years. If a lunar rock is found that currently contains 5 grams of ⁴⁰K, and it is determined that the sample contained 20 grams when it was formed, how old is the lunar rock? A) 6.5 billion years B) 19.5 billion years C) 2.6 billion years D) 3.9 billion years E) 4.6 billion years

Accepted Answer

We can use the formula for radioactive decay: 
amount remaining = initial amount x (1/2)^(t/half-life) 
where t is the time passed and half-life = 1.3 billion years.

We can plug in the given information: 
5 grams = 20 grams x (1/2)^(t/1.3 billion)

Divide both sides by 20 grams: 
1/4 = (1/2)^(t/1.3 billion)

Take the logarithm of both sides: 
log(1/4) = (t/1.3 billion) x log(1/2)

Simplify: 
log(1/4) = -2 
log(1/2) = -1

Therefore: 
-2 = (t/1.3 billion) x (-1) 
t/1.3 billion = 2 
t = 2 x 1.3 billion = 2.6 billion

Therefore, the lunar rock is 2.6 billion years old.

Question 13

The speed of the solar wind is approximately 400 km/s and the distance from the sun to Saturn is 9.5 AU (1 AU = 1.5*10⁸ km). How long does it take a particle in the solar wind to reach Saturn? A) about 4.1 hours B) about 4.1 days C) about 41 days D) about 4.1 years E) about 41 years

Accepted Answer

The distance from the Sun to Saturn is 9.5 AU, which is 9.5 * 1.5 * 10^8 km. The time taken is distance divided by speed, so (9.5 * 1.5 * 10^8 km) / (400 km/s) = 3.56 * 10^6 seconds, which is approximately 41 days.

Question 14

If a star is found with five planets orbiting it, and a process like that described in the solar nebula theory formed the planets, which of the planets would be expected to have the greatest uncompressed density?
A) The one farthest from the star.
B) The one with the greatest mass.
C) The one with the greatest radius.
D) The one closest to the star.
E) The one that has liquid water on its surface.

Accepted Answer

According to the solar nebula theory, planets closer to the star would have formed from denser materials and would have experienced higher temperatures, leading to a higher uncompressed density compared to the planets farther away from the star. Therefore, the planet closest to the star is expected to have the greatest uncompressed density.

Question 15

Condensation in the solar nebula probably led to the formation of
A) icy grains beyond the present orbit of Jupiter.
B) metallic grains near the present orbit of Mercury.
C) silicate grains near the present orbit of Earth.
D) all of the above.
E) none of the above.

Accepted Answer

Condensation in the solar nebula led to the formation of various types of grains including icy, metallic, and silicate grains at different distances from the Sun, hence option D is correct.

Question 16

On a photograph of the moon, the moon measures 30 cm in diameter and a small crater measures 0.2 cm. The moon's physical diameter is 1738 km. What is the physical diameter of the small crater?
A) about 1738 km
B) about 12 km
C) about 520 km
D) about 350 km
E) about 3.5 km

Accepted Answer

The answer of On a photograph of the moon, the...

Question 17

Once a terrestrial planet had formed from a large number of planetesimals, heat could have melted it and allowed it to differentiate into a metallic core of ____density and a rocky mantle or crust of ______ density.
A) higher; lower
B) lower; higher
C) Wrong! The interior stays solid.
D) Wrong! There is no separation according to density.

Accepted Answer

The metallic core would have a higher density than the rocky mantle or crust due to the heavier elements like iron and nickel sinking towards the center during differentiation, while lighter elements like silicon and oxygen remain in the upper layers.

Question 18

Suppose that Mercury grew to its present size in 1 million years through the accretion of particles averaging 100 g each. On average how many particles did Mercury capture each second? Note: Mercury has a mass of 3.3*10²³ kg and a radius of 2439 km. A) about 24 particles per second B) about 3.3*10²¹ particles per second C) about 67 particles per second D) about 100 million particles per second E) about 100 billion particles per second

Accepted Answer

The answer of Suppose that Mercury grew to its present...

Question 19

Part of the current atmosphere of Earth is believed to be
A) the remnants of the original hydrogen and helium gas from the solar nebula attracted by the protoplanet.
B) the result of the melting and vaporizing of the glaciers from the last ice age.
C) composed primarily of hydrogen and helium.
D) composed of gases that were outgassed from the heated rocks sometime after the planet formed.
E) the result of a collision between the sun and another star.

Accepted Answer

The current atmosphere of Earth is believed to be composed of gases that were outgassed from the heated rocks sometime after the planet formed. This process is known as outgassing or degassing, which occurred as a result of volcanic activity and the breakdown of minerals in rocks. Therefore, option D is the correct answer.

Question 20

The condensation sequence suggests that ____ should condense as solids closest to the sun.
A) hydrogen and helium
B) metals and metal oxides
C) silicates
D) ices of water, methane, and ammonia

Accepted Answer

The condensation sequence states that the materials with higher condensation temperatures will condense as solids closer to the sun. Metals and metal oxides have higher condensation temperatures than silicates and ices of water, methane, and ammonia, so they will be the first to condense as solids closest to the sun.

Quiz 15: The Origin of the Solar System

The age of the solar system is believed to be approximately 4.6 billion years based on the data from

The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because

Protoplanets of the Jovian planets could have grown very hot from

The uncompressed density of a planet in our solar system

The large planetesimals would have grown faster than the smaller planetesimals because

The most important effect in clearing the solar nebula of gas and dust was

If the terrestrial planets were formed by homogeneous accretion, then

Which one of the following objects is most like the planetesimals that formed in the solar nebula?

The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system?

Accretion among the grains in the solar nebula would have been aided by

What observation made of other stars seems to suggest the solar nebula theory is correct?

The diagram below illustrates the radioactive decay of Potassium (⁴⁰K) , which has a half-life of 1.3 billion years. If a lunar rock is found that currently contains 5 grams of ⁴⁰K, and it is determined that the sample contained 20 grams when it was formed, how old is the lunar rock?

The speed of the solar wind is approximately 400 km/s and the distance from the sun to Saturn is 9.5 AU (1 AU = 1.5*10⁸ km) . How long does it take a particle in the solar wind to reach Saturn?

If a star is found with five planets orbiting it, and a process like that described in the solar nebula theory formed the planets, which of the planets would be expected to have the greatest uncompressed density?

Condensation in the solar nebula probably led to the formation of

On a photograph of the moon, the moon measures 30 cm in diameter and a small crater measures 0.2 cm. The moon's physical diameter is 1738 km. What is the physical diameter of the small crater?

Once a terrestrial planet had formed from a large number of planetesimals, heat could have melted it and allowed it to differentiate into a metallic core of density and a rocky mantle or crust of __ density.

Suppose that Mercury grew to its present size in 1 million years through the accretion of particles averaging 100 g each. On average how many particles did Mercury capture each second? Note: Mercury has a mass of 3.3*10²³ kg and a radius of 2439 km.

Part of the current atmosphere of Earth is believed to be

The condensation sequence suggests that ____ should condense as solids closest to the sun.