Questions

To get a pair of black rings 100 percent certain

27 blue + 17 red + 2 black = 40 rings should be taken out

Then only we can get 100 % a pair of black rings. 

Astronomy is the study of planets and heavenly bodies. Historically, astronomy has focused on observations of heavenly bodies. It is a close cousin to astrophysics. Succinctly put, astrophysics involves the study of the physics of astronomy and concentrates on the behavior, properties and motion of objects out there.
 

The late Yashwantrao Balwantrao Chavan of the Congress(I) known as YB Chavan was given the official status of the Leader of the Opposition, with the rank of a Cabinet Minister, in the Lok Sabha, in 1977 by the janata Government.

Yashwantrao Balwantrao Chavan was the first Chief Minister of Maharashtra after the division of Bombay State and the fifth Deputy Prime Minister of India. He was a strong Congress leader, co-operative leader, social activist and writer. He was popularly known as Leader of Common People

Hence, Chavan was thus the first opposition leader to enjoy this status.

The Surface tension pulls the surface of the drop equally at all points thus produces the spherical shape having the minimum surface area. This surface tension is the "skin" of a body of water that makes the molecules stick together.