Answer: C) 8 Explanation: Let the number of boys = x From the given data, => [21x + 16(18)]/(x+16) = 19 => 21x - 19x = 19(16) - 16(18) => 2x = 16 => x = 8 Therefore, the number of boys in the class = 8.

Answer: D) Odontology Explanation: The study or scientific study of the structure, development, and abnormalities of the teeth is called Odontology. The science that studies teeth and their surrounding tissues, especially the prevention and cure of their diseases is called Dentology.

Answer: A) Geothermal Energy Explanation: Geothermal energy is heat energy generated and stored in the Earth. Geothermal energy has been used for thousands of years in some countries for cooking and heating. It is simply power derived from the Earth's internal heat.

Answer: D) All the above Explanation:

Answer: A) Capillary action phenomenon Explanation: Blotting paper absorbs ink by the process of capillary action. The capillary action is based on the property of surface tension of liquid.   All unsized paper will absorb water. Blotting paper is not sized and made bulkier to provide capillary action for faster absorption of liquid.   Blotting paper has also been sold as a cosmetic to aid in the removal of skin oils and makeup.

Answer: D) TIANHE 2 --- CHINA Explanation:

Answer: D) 8 Explanation: 9321 = 3 x 13 x 239 = 31 x 13 1 x 239 1 ; add one to all the powers ie., (1+1) x (1+1) x (1+1)= 8 ; we get eight factors.

Answer: B) Strontium Explanation: We know that, Elements in the same group of the periodic table have similar characteristics. Here Magnesium and Strontium shared some similar properties because they both belong to the same group. Sr is the chemical symbol for strontium which is a group two element; it has atomic number of 38.