Answer: A) H and Br Explanation: Only H and Br form Polar Covalent Bond.   Covalent bonding: Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability. 1. Polar Covalent Bond 2. Nonpolar Covalent Bond   1. Polar Covalent Bond: A Polar Covalent Bond is created when the shared electrons between atoms are not equally shared. This occurs when one atom has a higher electronegativity than the atom it is sharing with. The atom with the higher electronegativity will have a stronger pull for electrons (Similiar to a Tug-O-War game, whoever is stronger usually wins). As a result, the shared electrons will be closer to the atom with the higher electronegativity, making it unequally shared.   2. Nonpolar Covalent Bond: A Nonpolar Covalent Bond is created when atoms share their electrons equally. This usually occurs when two atoms have similar or the same electron affinity. The closer the values of their electron affinity, the stronger the attraction. This occurs in gas molecules; also known as diatomic elements. Nonpolar covalent bonds have a similar concept as polar covalent bonds; the atom with the higher electronegativity will draw away the electron from the weaker one.   Here H and H and N and N form Non-polar covalent bonds. Na and Br form the ionic bond.

Answer: C) 8, 4 Explanation: Let the number of girls = x => x + x + 4 = 12 => 2x = 8 => x = 4 => Number of girls = 4 => Number of boys = 4 + 4 = 8

Answer: D) Chandragupta Vikramaditya Explanation: Fahien came to India during the reign of Chandragupta Vikramaditya.

Answer: A) Trivandrum Explanation: Thiruvananthapuram also known as Trivandrum, is the capital and the largest city of the Indian state of Kerala is named after the snake Anantha of Lord Vishnu.

Answer: D) Specific enzymes breakdown proteins into amino acids Explanation: Protein digestion occurs in the stomach and duodenum in which 3 main enzymes:   1. Pepsin secreted by the stomach  2. Trypsin and 3. Chymotrypsin secreted by the pancreas   Break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids.

Answer: A) oxygen, nitrogen, carbon, hydrogen, sulfur, and phosphorus Explanation: Living organisms often contain trace amounts of several elements, but the most abundant ones are oxygen, carbon, hydrogen, nitrogen, calcium, sulphur and phosphorus.

Answer: B) France Explanation: France became the first country in the world to use drones for national mail service.

Answer: A) 91 Explanation: Prime Numbers :: Numbers which are divisible by only 1 and itself are Prime Numbers.   It's answer will be 91. Because 91 can be divisible by 7,13,91,1. It is quite clear that prime number should be divisible only by itself and by 1.