universe & solar system section 9 Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (a)

Earth’s early atmosphere contained only small amounts of free oxygen, probably produced entirely by the reaction of sunlight with water vapor from volcanoes. The oxygen-rich atmosphere that evolved later, and upon which oxygen-breathing life now depends, was a result of the origin of photosynthesis.

During the Precambrian, vast numbers of single-celled algae and cyanobacteria living in the seas eventually released enough oxygen to transform the environment.

Answer: (b)

Pluto was discovered by Clyde Tombaugh in 1930. According to International Astronomical Union (IAU) on August 24, 2006, Pluto is considered a dwarf planet. According to the definition, there are currently eight planets and five dwarf planets known in the solar system.

The five dwarf planets are Pluto, Ceres, Eris, Make make and Haumea. Pluto has been given number 134340.

Answer: (a)

Venus 'overtakes' the Earth every 584 days as it orbits the Sun.

As it does so, it changes from the 'Evening Star', visible after sunset, to the 'Morning Star', visible before sunrise.

Answer: (d)

Yes, the planets orbit in or close to a plane around the sun called the ecliptic.

The ecliptic is inclined 7 degrees from the planet of the Sun’s equator.

Answer: (d)

A. Semeru Volcano is situated in Indonesia.

B. Cotopaxi Volcano is situated in Ecuador.

C. Etna Volcano is situated in Italy.

D. Kilimanjaro Volcano is situated in Kenya.