universe & solar system section 12 Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (a)

The principle of Blackhole was enunciated by S. Chandrashekhar. A Black Hole is a region of space-time from which gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return.

The hole is called “black” because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.

Answer: (b)

The planet Pluto has been declared as a dwarf planet in the summit held in Prague. In August 2006 the International Astronomical Union (IAU) downgraded the status of Pluto to that of a “dwarf planet.”

This means that from now on only the rocky worlds of the inner Solar System and the gas giants of the outer system will be designated as planets.

Answer: (d)

Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, an ultraviolet light.

On Earth, sunlight is filtered through the Earth’s atmosphere, and is obvious as daylight when the Sun is above the horizon.

Answer: (b)

The Earth rotates around its axis from west to east. Earth’s rotation is the rotation of the solid Earth around its own axis. The Earth rotates from the west towards the east. As viewed from the North Star or polestar Polaris, the Earth turns counter-clockwise.

Answer: (b)

A. The smallest planet of the solar system is – Pluto

B. The largest planet of the solar system is – Jupiter

C. The planet second from the Sun in the solar system is – Venus

D. Planet nearest to the Sun is – Mercury.