Answer: C) Petrology Explanation: The scientific study of rocks is called petrology, which is an essential component of geology.

Answer: A) 4320 Explanation: Given Word is PROMISE. Number of letters in the word PROMISE = 7 Number of ways 7 letters can be arranged = 7! ways Number of Vowels in word PROMISE = 3 (O, I, E) Number of ways the vowels can be arranged that 3 Vowels come together = 5! x 3! ways   Now, the number of ways of arrangements so that three vowels should not come together = 7! - (5! x 3!) ways = 5040 - 720 = 4320.

Answer: A) 84 km/hr Explanation: Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively.Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr.Also, 6x = 72 => x = 12 km/hrTherefore, the average speed of the car and train together is = 5x+9x2= 7x = 7 x 12 = 84 km/hr.

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: C) 4 Explanation: Let the required number be 'N' given that its quarter i.e; N/4 exceeds its double i.e, 2N by 7 => N/4 + 7 = 2N => N + 28 = 8N 7N = 28 N = 4.

Answer: A) bonds Explanation: chemical energy is contained in the chemical bonds between the reactants in the chemical compounds.

Answer: C) 8 and 1 kmph Explanation: Downstream speed = 72km/8hrs  = 9 kmphupstream speed = 84km/12hrs = 7 kmphspeed of boat = avg of downstream and upstream speedsspeed of boat = (9+7)/2kmph = 8 kmph.current speed = half of the difference of downstream and upstream speedscurrend speed = (9-7)/2kmph = 1 kmph

Answer: C) Antarctica Explanation: Africa - 54 countries South America - 12 countries Antarctica - 0 countries Europe - 43 countries.   Hence, Antarctica continent has the least countries.