which of the following worlds have the thinnest lithospheres? A. Earth and Mars. B. Earth and its Moon. C. Mars and Venus. D. Earth and Venus. E. Mars and Earth’s Moon. 2) Which part of a comet points most directly away from the Sun? A. The dust tail. B. The plasma tail. C. The coma. D. The nucleus. 3) Sulfuric acid rain on Venus contributes to significant erosion of the planet’s surface. A. True B. False
The Correct Answer and Explanation is:
Sure! Let’s go through each question one by one with the correct answer and detailed explanation.
1) Which of the following worlds have the thinnest lithospheres?
Options:
A. Earth and Mars
B. Earth and its Moon
C. Mars and Venus
D. Earth and Venus
E. Mars and Earth’s Moon
Correct answer: D. Earth and Venus
Explanation:
The lithosphere is the rigid outer layer of a planet, consisting of the crust and the uppermost mantle. Its thickness varies depending on a planet’s internal heat, size, and geological activity.
- Earth has a relatively thin lithosphere compared to smaller, less geologically active bodies. This is because Earth is geologically active, with plate tectonics and mantle convection constantly reshaping the lithosphere. The lithosphere under oceanic crust is particularly thin, sometimes just 5-10 km thick, while continental lithosphere can be thicker but still relatively thin compared to other bodies.
- Venus is similar in size to Earth and also has a relatively thin lithosphere, though it does not have Earth-style plate tectonics. Venus’s lithosphere is believed to be relatively thin because of the planet’s high surface temperature and internal heat causing a softened mantle and some volcanic resurfacing.
- Mars and the Moon have thicker lithospheres due to their smaller sizes and less internal heat. They lack active plate tectonics and have largely solidified interiors, resulting in thick, rigid lithospheres. Mars’ lithosphere is estimated to be tens to hundreds of kilometers thick, much thicker than Earth’s.
Thus, Earth and Venus, being larger and hotter, have thinner lithospheres compared to Mars and the Moon, making option D correct.
2) Which part of a comet points most directly away from the Sun?
Options:
A. The dust tail
B. The plasma tail
C. The coma
D. The nucleus
Correct answer: B. The plasma tail
Explanation:
A comet has two types of tails when it approaches the Sun:
- Dust tail: Made of small solid particles pushed away from the comet by solar radiation pressure. This tail curves away from the comet’s orbit due to the dust’s inertia and solar radiation forces.
- Plasma tail (ion tail): Made of ionized gas that is swept directly away from the Sun by the solar wind (a stream of charged particles emitted by the Sun). The plasma tail always points almost exactly directly away from the Sun, regardless of the comet’s direction of travel.
- Coma: The nebulous envelope around the nucleus formed by sublimated gases and dust.
- Nucleus: The solid core of the comet.
Therefore, the plasma tail is the part that points most directly away from the Sun because it is pushed by the solar wind along magnetic field lines, making B the correct choice.
3) Sulfuric acid rain on Venus contributes to significant erosion of the planet’s surface.
Options:
A. True
B. False
Correct answer: B. False
Explanation:
Venus does have clouds containing sulfuric acid droplets, but these clouds are located very high in the atmosphere (about 50-70 km above the surface). While sulfuric acid is extremely corrosive, the rain itself evaporates long before reaching the surface due to the planet’s intense heat (surface temperatures around 465°C).
As a result, the sulfuric acid rain does not reach the surface in liquid form to cause erosion. Instead, Venus’s surface features are shaped more by volcanic activity and tectonic processes rather than chemical weathering from acid rain.
Therefore, sulfuric acid rain on Venus does not contribute significantly to erosion, so the correct answer is B. False.
!