Consider the following statements about some planets in the solar system: 1. Mercury has no atmosphere. 2. Venus has two moons. 3. There is no land on Jupiter. 4. Rings of Saturn are composed of lumps of ice and dust. Which of the statements given above are correct?
- (a)1 and 2 only
- (b)3 and 4 only
- (c)1, 2 and 3
- (d)1, 3 and 4
Correct — D, 1, 3 and 4. Take the four in turn against what NASA publishes. Mercury has no atmosphere in the ordinary sense — instead of one it carries a thin exosphere of atoms knocked off the surface by the solar wind and by meteoroid strikes, mostly oxygen, sodium, hydrogen, helium and potassium, far too tenuous to behave as a gas envelope, so statement 1 passes. Jupiter is a gas giant with no true surface, mostly swirling gases and liquids of roughly solar composition, hydrogen and helium; there is nothing to land on, so statement 3 passes. Saturn's rings are billions of chunks of ice and rock coated with dust, ranging from icy grains no bigger than dust to blocks the size of a house, so statement 4 passes. Statement 2 is the one that fails: Venus has no moon at all. It is one of only two planets in the solar system without one, the other being Mercury. That leaves 1, 3 and 4.
- (a)1 and 2 only — Accepts the false moon claim and drops two true statements about Jupiter and Saturn.
- (b)3 and 4 only — Correct as far as it goes but throws away statement 1. Mercury genuinely has no atmosphere — only an exosphere, which is not the same thing.
- (c)1, 2 and 3 — The trap option. It keeps the two obvious truths, adds the Venus moon claim, and drops the Saturn ring statement, which is the least controversial of the four.
The solar system's eight planets fall into two families. The four inner ones — Mercury, Venus, Earth and Mars — are rocky, small and poor in moons; Mercury and Venus have none, Earth one, Mars two captured asteroids. The four outer ones — Jupiter, Saturn, Uranus and Neptune — are giants of gas or ice with deep atmospheres, no solid surface to speak of, ring systems and dozens of moons each. Saturn's rings are the brightest and best studied, but all four giants have rings.
Multi-statement astronomy items are usually decided by the one claim that can be settled without any arithmetic, and here that is the moon count. Mercury and Venus are the two moonless planets — a fact worth memorising as a pair, because examiners rotate which of the two they attach the false moon to. The subtler statement is the first: Mercury does have something above its surface, and a strict reading might resist calling it 'no atmosphere'. NASA's own wording settles it — instead of an atmosphere, Mercury possesses a thin exosphere — and the exosphere is continuously blown off and replenished rather than retained, so it is not an atmosphere in the sense the question means.
- Mercury has no atmosphere, only a thin exosphere of atoms driven off the surface by the solar wind and meteoroid impacts.
- Mercury and Venus are the only two planets in the solar system with no moons.
- Jupiter is a gas giant with no true surface, composed mainly of hydrogen and helium like the Sun.
- Saturn's rings are made of chunks of ice and rock coated with dust, from grain-sized particles to pieces as large as a house.
- Venus's atmosphere is mostly carbon dioxide with sulphuric acid clouds, and its surface pressure is about ninety-three times Earth's at sea level.
- Granting Venus a moon; it and Mercury are the two that have none.
- Arguing that Mercury's exosphere counts as an atmosphere — NASA's own description separates the two.
- Believing only Saturn has rings; Jupiter, Uranus and Neptune have fainter ring systems too.
As a four-statement planetary item mixing one false claim about moons or rings with three textbook truths.
Match List I with List II and select the correct answer by using the codes given below the lists: List I (Special Characteristic) I. Farthest planet from the Sun II. Largest planet of the solar system III. Planet second from the Sun in the solar system IV. Planet nearest to the Sun List II A) Mercury B) Venus C) Jupiter D) Pluto E) Saturn
- (a) I-B, II-C, III-E, IV-A
- (b) I-C, II-E, III-A, IV-B
- (c) I-D, II-A, III-B, IV-C
- (d) I-D, II-C, III-B, IV-A
Answer(d) I-D, II-C, III-B, IV-A
The same set of planets tested as a matching item. It is also a reminder that this material dates: Pluto was still counted a planet when that paper was set, and was reclassified as a dwarf planet in 2006.
- practice — not a real PYQ
Which two planets of the solar system have no moons?
- (a)Mercury and Venus
- (b)Venus and Mars
- (c)Mercury and Mars
- (d)Mars and Neptune
Answer(a) Mercury and Venus — the only two planets without a natural satellite.
- practice — not a real PYQ
Saturn's rings are composed mainly of which one of the following?
- (a)Liquid methane
- (b)Chunks of ice and rock coated with dust
- (c)Ionised hydrogen gas
- (d)Molten silicate rock
Answer(b) Chunks of ice and rock coated with dust — ranging from dust-sized icy grains to pieces as large as a house.