Understanding Planet Density

The question asks us to arrange specific planets in descending order based on their density. Density is a measure of how much mass is contained in a given volume. It is often expressed in grams per cubic centimeter (gm/cm³).

The density of a planet depends mainly on its composition. Terrestrial planets, like Earth and Venus, are primarily made of rock and metal, making them relatively dense. Gas giants, like Jupiter and Saturn, are composed mostly of lighter elements such as hydrogen and helium, resulting in much lower densities.

Comparing Densities of Earth, Venus, Jupiter, and Saturn

Let's look at the approximate average densities of the planets mentioned in the question:

From the table, we can see the density values:

• Earth: 5.52 gm/cm³
• Venus: 5.24 gm/cm³
• Jupiter: 1.33 gm/cm³
• Saturn: 0.69 gm/cm³

Arranging Planets in Descending Order of Density

Descending order means arranging from the highest density to the lowest density. Based on the values:

1. Earth has the highest density (5.52 gm/cm³).
2. Venus has the second highest density (5.24 gm/cm³).
3. Jupiter has the third highest density (1.33 gm/cm³).
4. Saturn has the lowest density among these four (0.69 gm/cm³).

Therefore, the correct descending order of density is:

\(\text{Earth} > \text{Venus} > \text{Jupiter} > \text{Saturn}\)

Verifying the Options

Let's compare our derived order with the given options:

• Option 1: Earth > Jupiter > Venus > Saturn (Incorrect, Jupiter is less dense than Venus)
• Option 2: Jupiter > Earth > Saturn > Venus (Incorrect, Jupiter is much less dense than Earth and Venus)
• Option 3: Earth > Venus > Jupiter > Saturn (Correct, matches our derived order)
• Option 4: Earth > Venus > Saturn > Jupiter (Incorrect, Saturn is less dense than Jupiter)

The correct sequence in descending order of density is Earth, Venus, Jupiter, and Saturn.

Revision Table: Planet Properties

This table summarizes the key information regarding the type and density of each planet, making it easy to review and understand the ranking.

Additional Information: Why Densities Vary

The significant difference in density between terrestrial planets (Earth, Venus) and gas giants (Jupiter, Saturn) is a fundamental characteristic that classifies planets. Terrestrial planets are rocky and metallic, formed closer to the Sun where lighter, volatile materials were driven away by solar heat. Gas giants formed further out, accumulating vast amounts of hydrogen and helium. Interestingly, Saturn is less dense than water (approximately 1 gm/cm³), meaning it would float in a large enough body of water.