Geo & Env (Each Tuesday)
1. Consider the following statements regarding asteroids: 1. Asteroids are rocky debris of varying sizes orbiting the Sun. 2. Most of the asteroids are small but some have diameter as large as 1000 km. 3. The orbit of asteroids lies between orbits of Jupiter and Saturn. Which of the statements given above are correct? (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 (a) Asteroids are rocky debris of varying sizes orbiting the Sun. They are generally small but some has the diameter of 1000 km. Asteroids are minor planets whose orbits lie between Jupiter and Mars. These are said to be the fragments of a larger planet disrupted long ago. Their number is estimated to be 30,000 pieces of rocky debris out of which more than half are known. 2. Which one of the following statements is correct with reference to our solar system? (a) The earth is the densest of all the planets in our solar system. (b) The predominant element in the composition of Earth is silicon. (c) The Sun contains 75 percent of the mass of the solar system. (d) The diameter of the sun is 190 times that of the Earth. (a) The Earth is the densest planet in the solar system. The density of Earth is 5.513g/cm3. This is an average of all the material on the planet. 3.Diamond Ring is a phenomenon observed (a) at the start of a total solar eclipse. (b) at the end of a total solar eclipse. (c) only along the peripheral regions of the totality trail. (d) only in the central regions of the totality trail. (c) Diamond Ring is the phenomenon which occurs along the peripheral regions of the totality tail. As the last bits of sunlight pass through the valleys on the moon’s limb, and the faint corona around the sun is just becoming visible, it looks like a ring with glittering diamonds on it. 4. The tail of a comet is directed away from the sun because (a) the comet rotates around the sun, the lighter mass of the comet is pushed away due to the centrifugal force alone. (b) the comet rotates, the lighter mass of the comet is attracted by some star situated in the direction of its tail. (c) The radiation emitted by the sun exerts a radial pressure on the comet throwing its tail away from the Sun. (d) The tail of the comet always exists in the same orientation. (a) The tail of the comet is always away from the Sun because the comet rotates around the Sun, the lighter mass of the comet is pushed away due to the centrifugal force alone. The tail of a comet is made up of gas and tiny particles that are carried away from the sun by the solar wind. Comets are formed mostly from ice and dust, and their tails only form when they are close enough to be melted by heat from the sun. As the nucleus of a comet begins to melt, it forms a cloud of gas and small particles known as the coma. When comets travel close enough into the center of our solar system, pressure from sunlight causes the coma to form a tail that stretches away from the sun. 5. Consider the following two statements, one labeled as the Assertion (A) and the other as Reason (R). Examine these two statements carefully and select the correct answer using the codes given below: Assertion (A): The same face of the Moon is always presented to the Earth. Reason (R): The Moon rotates about its own axis in days which is about the same time that it takes to orbit the earth. Codes: (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true, but R is not the correct explanation of A. (c) A is true, but R is false. (d) A is false, but R is true. (a) The same side of the Moon is always faces the Earth because the Moon spins once on its axis in exactly the same amount of time that the Moon revolves around the Earth.
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