Space

Black-hole is–

Assertion (A): Black hole is such a celestial existence which cannot be seen by telescope. Reason (R) : The gravitational field of black hole is much strong that even light does not escape from it.

Black Hole –

The tail of a comet always points –

Highly dense stars are called–

In the universe, what are pulsars?

Consider the following pairs : Objects in space – Description 1. Cepheids – Giant clouds of dust and gas in space 2. Nebulae – Stars which brighten and dim periodically 3. Pulsars – Neutron stars that are formed when massive stars run out of fuel and collapse How many of the above pairs are correctly matched?

Electrically charged particles from space travelling at speeds of several hundred km/sec can severely harm living beings if they reach the surface of the Earth. What prevents them from reaching the surface of the Earth?

If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth ? 1. GPS and navigation systems could fail. 2. Tsunamis could occur at equatorial regions. 3. Power grids could be damaged. 4. Intense auroras could occur over much of the Earth. 5. Forest fires could take place over much of the planet. 6. Orbits of the satellites could be disturbed. 7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted. Select the correct answer using the codes given below :

Assertion (A): A space shuttle loses radio contact with ground station for a while during landing on the Earth. Reason (R): As a space shuttle enters Earth's atmosphere, the shuttle's surface temperature increases which ionize the surrounding air. In the context of the above statements, which of the following is correct?