SSC CHSL – SSC CHSL Test 22

Read the following passage carefully and answer the given questions. <br><br> From a vantage point in space, an observer could see that the Earth is engaged in a variety of motions. First, there is its rotation on its own axis, causing the alternation of day and night. This rotation, however, is not altogether steady. Primarily because of the moon's gravitational action, the Earth's axis <strong>wobbles</strong> like that of an ill­spun top. In this motion, called 'precession', the North and South Poles each traces out the base of a cone in space, completing a circle every 25,800 years, In addition, as the Sun and the Moon change their positions with respect to the Earth, their changing gravitational effects result in a slight 'nodding' of the earth's axis, called 'mutation', which is superimposed on precession. The Earth completes one of these 'nods' every 18.6 years. The earth also, of course, revolves round the Sun, in a 6­million mile journey that takes 365.25 days. The shape of this orbit is an ellipse, but it is not the center of the Earth that follows the elliptical path. Earth and Moon behave like an asymmetrical dumb­bell, and it is the center of mass of this dumb­bell that traces the ellipse around the sun. The center of the Earth­Moon mass lies about 3000 miles away from the center of the Earth, and the Earth thus moves in an S­curve that crosses and re­ crosses its orbital path. Then too, the Earth accompanies the sun in the sun's movements: first, through its local star cloud, and second, in a great sweep around the hub of its galaxy, the Milky Way that takes 200 million years to complete.

The alternation of day and night on the Earth is due to

Read the following passage carefully and answer the given questions. <br><br> From a vantage point in space, an observer could see that the Earth is engaged in a variety of motions. First, there is its rotation on its own axis, causing the alternation of day and night. This rotation, however, is not altogether steady. Primarily because of the moon's gravitational action, the Earth's axis <strong>wobbles</strong> like that of an ill­spun top. In this motion, called 'precession', the North and South Poles each traces out the base of a cone in space, completing a circle every 25,800 years, In addition, as the Sun and the Moon change their positions with respect to the Earth, their changing gravitational effects result in a slight 'nodding' of the earth's axis, called 'mutation', which is superimposed on precession. The Earth completes one of these 'nods' every 18.6 years. The earth also, of course, revolves round the Sun, in a 6­million mile journey that takes 365.25 days. The shape of this orbit is an ellipse, but it is not the center of the Earth that follows the elliptical path. Earth and Moon behave like an asymmetrical dumb­bell, and it is the center of mass of this dumb­bell that traces the ellipse around the sun. The center of the Earth­Moon mass lies about 3000 miles away from the center of the Earth, and the Earth thus moves in an S­curve that crosses and re­ crosses its orbital path. Then too, the Earth accompanies the sun in the sun's movements: first, through its local star cloud, and second, in a great sweep around the hub of its galaxy, the Milky Way that takes 200 million years to complete.

The word which is nearly same in meaning to the word 'wobble' is

Read the following passage carefully and answer the given questions. <br><br> From a vantage point in space, an observer could see that the Earth is engaged in a variety of motions. First, there is its rotation on its own axis, causing the alternation of day and night. This rotation, however, is not altogether steady. Primarily because of the moon's gravitational action, the Earth's axis <strong>wobbles</strong> like that of an ill­spun top. In this motion, called 'precession', the North and South Poles each traces out the base of a cone in space, completing a circle every 25,800 years, In addition, as the Sun and the Moon change their positions with respect to the Earth, their changing gravitational effects result in a slight 'nodding' of the earth's axis, called 'mutation', which is superimposed on precession. The Earth completes one of these 'nods' every 18.6 years. The earth also, of course, revolves round the Sun, in a 6­million mile journey that takes 365.25 days. The shape of this orbit is an ellipse, but it is not the center of the Earth that follows the elliptical path. Earth and Moon behave like an asymmetrical dumb­bell, and it is the center of mass of this dumb­bell that traces the ellipse around the sun. The center of the Earth­Moon mass lies about 3000 miles away from the center of the Earth, and the Earth thus moves in an S­curve that crosses and re­ crosses its orbital path. Then too, the Earth accompanies the sun in the sun's movements: first, through its local star cloud, and second, in a great sweep around the hub of its galaxy, the Milky Way that takes 200 million years to complete.

What causes mutation?