# National Standard Examination in Astronomy (NSEA) Solved Paper 2016 Part-19

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Q: 66. A star in prime age is said to be under equilibrium due to gravitational pull and outward radiation pressure (P). Consider the shell of thickness dr as in the figure of question (65). If the pressure on this shell id dp then the correct equation is (G is universal gravitational constant)

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Answer: (A)

Q: 67. In astronomy order of magnitude estimation plays an important role. The derivative can be taken difference ratio Consider the star has a radius R, pressure at its centre is and pressure at outer layer is zero if the average mass is and average radius then the expression for is

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Answer: (A)

Q: 68. The value of mass and radius of sum are given by kg and respectively. The pressure at the centre is about .

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Answer: (C)

Q: 69. Assuming that the gas inside the sun behaves very much like the perfect gas, the temperature at the centre of the sun is nearly (the number density of gas particles =), Boltzmann constant = and mass of proton

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Answer: (B)

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