The logical answer for a puzzle is that the letter 'W'.   A rainbow is a spectrum of light that appears in the sky when sunlight is refracted through raindrops or other drops of moisture in the Earth's atmosphere. They have inspired much popular folklore, including the belief that a leprechaun can be found with a pot of gold at the end of a rainbow.

Answer: A) Longitudinal waves Explanation: Compressions and Rarefactions are characteristic of Longitudinal waves. The direction of vibration of the particles is in the same plane as in which the wave is propagating. The particles vibrate back and forth, about their mean positions.

Answer: B) Rs. 10,500 Explanation: The ratio of distribution should be: 21 x 15 : 15 x 35 : 35 x 21= 315 : 525 : 735 = 3 : 5 : 7The smallest share will be of worth: 3/15 x 52,500 = Rs. 10,500

Answer: D) a puzzle box Explanation: Edward Thorndike (1874 - 1949) is famous in psychology for his work on learning theory that lead to the development of operant conditioning within behaviorism. Thorndike (1898) studied learning in animals (usually cats). He devised a classic experiment in which he used a puzzle box to empirically test the laws of learning.

Answer: A) Diamond Explanation: Diamond is the hardest substance available on Earth. Diamond is the hardest substance available on Earth due to the giant molecular structure of diamond in which each carbon atom is covalently bonded to four other carbon atoms. A covalent bond is very strong and requires a large amount of energy to break itself, and diamond has many covalent bonds.

Answer: C) Chalkboard Explanation: It is Blackboard or Chalkboard which is Black when clean, and as you write on it with white chalk it becomes dirty in White color.

Answer: B) 12, 18, 36, Explanation: The Multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48, 54, 60. The Multiples of 4 are 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60. The Common Multiples of 4 & 6 upto 60 numbers are given as 12, 24, 36, 48, 60.

Answer: D) HDFC Bank Explanation: