Universe - Study Mode
[#81] What is "Supernova"?
Correct Answer
(D) Black Hole
Explanation
Solution: The most likely 'cannon' is the explosive kick of a supernova, one of the Universe's most titanic events. When massive stars end their lives, they explode violently as supernovae. They leave either a neutron star or a black hole as a remnant, depending on how massive the star initially is.
[#82] Which two planets of the solar system have no satellites?
Correct Answer
(A) Mercury and Venus
Explanation
Solution: Mercury and Venus are too close to the Sun. Any moon with too great a distance from these planets would be in an unstable orbit and be captured by the Sun. If they were too close to these planets they would be destroyed by tidal gravitational forces.
[#83] If there is no Sun, the colour of the sky would be ________
Correct Answer
(D) Black
Explanation
Solution: The sky appears blue because the sunlight is scattered by the gas molecules in the atmosphere - a phenomenon known as Rayleigh scattering - named after the discoverer - a British physicist who also discovered Argon - Lord Rayleigh (1842-1919). So, if there was no atmosphere, the sky would appear black.
[#84] The planet Mercury is difficult to be observed most of the time because ________
Correct Answer
(C) It being too close to the Sun, gets hidden by the glare of the Sun
Explanation
Solution: The planet Mercury is often cited as the most difficult of the five brightest naked-eye planets to see. Because it's the planet closest to the Sun, it never strays too far from the Sun's vicinity in our sky.
[#85] The correct sequence of planets in the descending order of their equatorial diameter is ________
Correct Answer
(D) Uranus, Earth, Mars, Mercury
Explanation
Solution: The correct sequence of planets in the descending order of their equatorial diameter is Uranus, Earth, Mars, Mercury.