Question

A planet which is called born sister of Earth is
(A) Mercury
(B) Venus
(C) Mars
(D) Jupiter

Answer 1

We have to compare the size and the mass of earth with those of the other planets given in the options. The one with mass and size nearly the same as that of the earth will be called the born sister of earth.

Complete step-by-step solution:
We know that the planets are approximately solid spheres. Two solid spheres are physically distinguished by the physical properties such as density, size, mass etc.
We know that the mass of earth is approximately equal to $5.97 \times {10^{24}}kg$ . Also, its radius is approximately equal to $6378{\text{ km}}$. So the planet whose mass and radius are close to these values will be called as the born sister of earth.
The mass of mercury is approximately $3.28 \times {10^{23}}km$, and its radius is approximately equal to $2439.7{\text{ km}}$. As can be clearly seen, these are far from the respective values of the mass and the radius of the earth. So the mercury planet cannot be called as the born sister of earth.
Now, the mass of mars is approximately equal to $6.39 \times {10^{23}}km$, and its radius is approximately $3389.5{\text{ km}}$. These values are also not close to the respective values for the earth. So mars can also not be called the born sister of Earth.
We know that Jupiter is the largest planet in the solar system. So its size must be definitely much greater than that of the earth. So definitely, it cannot be the born sister of Earth.
Now, the mass of Venus is approximately equal to $4.87 \times {10^{24}}kg$ and its radius is equal to $6051{\text{ km}}$. So we see that the mass and the radius of Venus are nearly the same as that of Earth. So it can be called the born sister of Earth.

Hence, the correct answer is option B.

Note: Although the size and the mass of Venus is nearly the same as that of the earth, it doesn’t mean that life can be possible on Venus just like that on the Earth. Due to the thick atmosphere of Venus, the atmospheric pressure is about ninety times more than that of the earth. Also, its surface has extreme temperatures. These altogether make life impossible there