The features of the planet Saturn are: a.    It has a brightest concentric ring which is made up of ice, dust particles which revolves around it. b.    It is the second largest planet in the solar system. c.   .....

The reasons for the existence of living beings on the earth are: a.    The earth is at a suitable distance from the sun. b.    The earth has atmosphere and all the gases required for the life of .....

The Pluto has been omitted from the list of the planet in the solar system because of the following reasons: a.    Its orbit does not lie on the same plane of the orbit of the other planets. b.    It intersects the .....

The group of stars having a specific shape is called a .....

A black hole is a heavenly body or point in space which has infinite density and gravity such that even light falling on it can’t .....

Galaxy is a giant assembly of billions of stars, interstellar gas and dust particles forming their own cluster in the universe all held together by .....

The unburned masses of the meteors that reach the earth’s surface are called .....

Meteors are the bright streak of light seen for a short duration of time in the sky on a clear .....

Stars are celestial bodies, consisting of a large, self-luminous mass of hot gas held together by their own .....

The planets which are far away from the sun and lying beyond the asteroid belt are called outer .....

A relatively small, solid celestial body moving in orbit around a star, particularly the sun is called a .....

The family of the sun which includes eight planets, their satellites, meteors, meteorites, comets, asteroids, etc. that move around the sun is called the solar .....

The various harmful gases like carbon dioxide, carbon monoxide, sulphur dioxide, nitrogen oxide, etc. which are produced by the industries are called industrial gases. Acid rain is a rain or any other form of precipitation that is usually acidic. It .....

The depletion of ozone layer is the formation of a hole in it or gradual thinning of this layer. Depletion of the ozone layer is caused due to the entry of chemicals like chlorofluorocarbon (CFCs), methyl chloroform, carbon tetrachloride, etc. into .....

a.  It is due to the depletion of ozone layer depletion. b. We should conserve the ozone layer to control this situation. c.  Due to ozone layer depletion, more ultraviolet rays and more radiation of the sun enter the surface .....

a.    Stratosphere  The layer of atmosphere above the troposphere is called the stratosphere. It is extended up to 16 km to 50 km above the earth’s surface. This region is also called ozonosphere. The ozone layer protects .....

The ozone layer is a region of earth’s stratosphere that absorbs most of the sun’s ultraviolet radiation. It contains high concentrations of ozone. Ozone consists of three atoms of oxygen. The ozone layer is called protective layer .....

Moon is the natural satellite of earth.  Manmade satellites are known as an artificial satellite.  The two reasons for launching artificial satellites into space are: a. Weather forecast, research b. .....

The international efforts to minimize the climate change are: a.    The United Nation Framework Convention on Climate Change (UNFCCC) It was held in the year 1992 in Rio de Jene Rio. This conference addressed various aspects like .....

The national efforts to minimize the climate change are: a.    National Communication Report In this report, Nepal has mentioned the impacts of climate change, additional ways to the change and various policies and laws to be .....

Kyoto protocol was adopted in December 1997 A.D. Its main objective is to reduce climate change and production of greenhouse gases to control global warming. The protocol makes 36 developed countries of the world to reduce the emission of green .....

The uses of chlorofluorocarbon are: a.    They are used as refrigerants. b.    They are used in the manufacturing of blowing agents for foams and packing materials. c.    They are used in an aerosol spray .....

The depletion of ozone layer is the formation of a hole in it or gradual thinning of this layer. Depletion of the ozone layer is caused due to the entry of chemicals like chlorofluorocarbon (CFCs), methyl chloroform, carbon tetrachloride, etc. into .....

The effects seen in human health due to the depletion of ozone layer are: a.    It may cause skin inflammation. b.    Different types of cancers, cataract, loss of immunity, etc. are caused due to it. c.   .....

Ozone is created primarily in the stratosphere by ultraviolet radiation. When high-energy ultraviolet rays strike on ordinary molecules, they split the molecules into two single oxygen atoms, known as atomic oxygen. A freed oxygen atom then combines .....

The gases which are responsible for greenhouse effect are called greenhouse .....

The rain containing acids that are formed in the atmosphere when industrial gas emissions combine with water is called acid .....

The uppermost layer of the mesosphere is called .....

An ozone hole is the region of space in the stratosphere where the amount of ozone content has been reduced .....

The different gases like sulphur dioxide, carbon dioxide, nitrous oxide, etc. which are produced by industries are called industrial .....

The layer of atmosphere which lies just above the stratosphere is called .....

The layer of atmosphere which lies just above the troposphere is called the .....

The envelope of air that surrounds the earth is called .....

a.    Pre Cambrian era Pre Cambrian era started about 4.6 billion years ago and ended 570 million years ago. It is the combination of the archeozoic, Proterozoic and Cenozoic era. The early part of this era is the beginning of the .....

Cenozoic era began 65 years ago and still going on. The first primates and horses were evolved in this era. Mammals, birds and insects were spread. Rhinoceros, camels, elephants, first modern mammals were evolved during this era. Angiosperm spread .....

The Palaeozoic era began 570 million years ago and ended about 250 million years ago. Aquatic and terrestrial vertebrates and invertebrates evolved in this era. The first vertebrate appeared in the form of primitive fish, some fish had lungs and .....

The Mesozoic era began about 250 million years ago and ended 65 million years ago. Mammals and birds began to evolve at the end of this era. The giant reptiles like dinosaurs evolved, flourished and were extinct. Turtles, crocodile-like species and .....