CBSE Questions for Class 8 General Knowledge General Physical Geography Quiz 11 - MCQExams.com

• If plants stop releasing oxygen into the atmosphere the ecological balance would be disturbed. Organisms including humans would be affected due to the reduction in the number of oxygen levels. 
• It also causes genetic mutations and hormonal changes that can affect the reproductive capacity of many organisms.

• Magma is extremely hot liquid and semi-liquid rock located under Earth’s surface. It is a mixture of molten or semi-molten rock, volatiles and solids.
• Besides molten rock, it may contain suspended crystals and dissolved gases. When magma flows onto Earth’s surface, it is called Lava.

• A geyser is a vent in Earth's surface that periodically ejects a column of hot water and steam. They are a quite rare phenomenon on Earth due to the precise conditions that are required for them to form. They are mainly clustered near active volcanic areas. 
• The Taupo Volcanic Zone in New Zealand is 350 km long and 50 km wide and contains volcanoes, hot springs and geysers. The largest geyser ever known, the Waimangu Geyser, sat in the Taupo Volcanic Zone.

It’s an alignment of three celestial objects, as the sun, the earth, and either the moon or a planet: Syzygy in the sun-earth-moon system occurs at the time of full moon and new moon.

The time when the Sun crosses the plane of the Earth's equator, making night and day of approximately equal lengths all over the Earth is called An equinox is commonly regarded as the instant of time when the plane of Earth's equator passes through the center of the Sun.

• Meteorology is the study of the atmosphere. 
• A meteorologist is an individual with specialized education who uses scientific principles to explain, understand, observe or forecast the earth's atmospheric phenomena. 
• They also study how the atmospheric and weather conditions affect the earth and its human inhabitants.

• Widely regarded as one of the greatest scientists, Galileo Galilei was an Italian astronomer, physicist, engineer and mathematician, who helped shape the scientific revolution during the Renaissance. 
• He discovered Jupiter’s four largest moons viz. Io, Europa, Ganymede, and Callisto. They are together known as the Galilean Satellites in his honour.

• Indian Standard Time (IST) is the time observed throughout India, with a time offset of UTC+05:30.
• It is calculated on the basis of 82.5' E longitude, in Mirzapur (Amravati Chauraha), Uttar Pradesh, which is nearly on the corresponding longitude reference line.

• Moraines are accumulations of dirt and rocks that have fallen onto the glacier surface or have been pushed along by the glacier as it moves.
• The dirt and rocks composing moraines can range in size from powdery silt to large rocks and boulders.
• A receding glacier can leave behind moraines that are visible long after the glacier retreats.

• New Horizons is a space probe launched by NASA on 19 January 2006, to the dwarf planet Pluto and on an escape trajectory from the Sun. It is the first man-made spacecraft to go to Pluto.
• The primary mission of New Horizons is to study Pluto and its system of moons. The secondary mission is to study any objects in the Kuiper Belt, if something became available for a flyby.

• The Soyuz is widely considered the world's safest, most cost-effective human spaceflight vehicle.
• Soyuz spacecraft were used to carry cosmonauts to and from Salyut and later Mir space stations, and are now used for transport to and from the International Space Station.
• Atleast one Soyuz spacecraft is docked at the ISS at all times for use as an escape craft in the event of an emergency. 

• A black hole does not have a surface, like a planet or star. Instead, it is a region of space where matter has collapsed in on itself.
• This catastrophic collapse results in a huge amount of mass being concentrated in an incredibly small area.
• The gravitational pull of this region is so great that nothing can escape, not even light.

• Orbital debris is "junk" that is circling Earth. It is pieces from spacecraft. Humans have been launching objects into space for more than 50 years. Most of those objects have fallen back to Earth.
• A piece of debris falls back to Earth about once a day. These objects either land or burn up in the atmosphere.
• Most objects that return to Earth end up in water, since it makes up 70 percent of Earth's surface. But many of the objects sent into space are still in orbit around Earth.

• Neutron stars are city-size stellar objects with a mass about 1.4 times that of the sun.
• They are created when giant stars die in supernovas and their cores collapse, with the protons and electrons essentially melting into each other to form neutrons.
• The gravity on a neutron star is 2 billion times stronger than gravity on Earth.

• Leo constellation lies in the northern sky. It is one of the zodiac constellations and one of the largest constellations in the sky.
• Leo is a highly recognizable constellation, as it is one of the few constellations that resemble its namesake.
• It can be seen in the northern hemisphere in the spring. It is visible at latitudes between 90 degrees and -65 degrees.

• The gravitation force of a planet depends on its density, mass and size.
• Mars is similar to Earth in many key respects but when it comes to size, mass and density, it is comparatively small. Hence, the gravity of Mars is about one-third of Earth.
• Similarly, Pluto being a dwarf planet has considerably less mass and density than Earth. Thus, its gravity is about one-fifteenth of Earth.

• Comet Shoemaker-Levy 9 was a comet. It broke apart and crashed into Jupiter, in July 1994. The event was special because people could see, for the first time, how objects in the Solar System, outside Earth, collided.
• The comet was carefully watched by astronomers worldwide. The crash gave new information about Jupiter. It also showed up its role in reducing space debris in the inner Solar System.

• A galaxy is a collection of stars and interstellar material held together by gravity. The galaxy our Sun lives in is called the Milky Way.
• The name `Milky Way' comes from the band of light that is seen overhead on very dark nights.
• A thick layer of interstellar dust hides much of the Galaxy from observation by optical telescopes, and astronomers can determine its large-scale structure only with the aid of radio and infrared telescopes, which can detect the forms of radiation that penetrate the hidden matter.

• Ganymede is Jupiter’s largest moon and also the largest moon in the solar system.
• It is the only moon with its own magnetic field. The magnetic field causes auroras, which are ribbons of glowing, electrified gas, in regions circling the moon’s north and south poles.

• Venus has more volcanoes than any other planet in the solar system. Over 1600 major volcanoes or volcanic features are known and there are many smaller volcanoes.
• The volcanoes of Venus take unusual shapes, but they are all classified as "shield volcanoes" like those which occur in Hawaii, USA.

• The Sea of Tranquility is the landing site of Apollo 11, the mission that gave mankind its first ever walk on the Moon.
• It is a dark spot located in the northern hemisphere of the Moon. The sea is not a body of water but a lower-altitude plain.
• As a result of earlier periods of lunar volcanism, it is filled with dark, solidified lava.