Answer: Option A. -> Stagnation of water on road
Tar roads gets damaged easily during rainy season. This is because tar roads are prone to water damage very quickly. In the tar road, bitumen plays an important road to create a bond between the aggregate. But, tar road does not give more strength than concrete road, because bitumen respond to heat and water.

Answer: Option D. -> Disinfectant
UV radiation can be an effective viricide and bactericide. Disinfection using UV radiation is commonly used in wastewater treatment applications and is finding an increased usage in drinking water treatment.

Answer: Option B. -> Amount of oxygen used for biochemical oxidation
Clean water has BOD which is less than 5 ppm. If it is equal to or more than 12 ppm, then the water is considered as polluted. So this indicates water be rich in dissolved oxygen, that helps the microorganisms to oxidize inorganic and organic materials.

Answer: Option D. -> CO2
Aerated water is, correctly speaking, water to which air is added. So aerated water is any water artificially impregnated with a large amount of gas (as carbon dioxide). The term is, however, frequently applied to carbonated water.

Answer: Option D. -> Oxygen
Water pollution in river or any other water body is measured by amount of dissolved oxygen.

Answer: Option D. -> Carbon-14
Radiocarbon dating (usually referred to as simply carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. After plants die or they are consumed by other organisms (for example, by humans or other animals), the incorporation of all carbon isotopes, including 14C, stops. Thereafter, the concentration (fraction) of 14C declines at a fixed exponential rate due to the radioactive decay of 14C.

Answer: Option B. -> Mo
Molybdenum (Mo) acts as promoter for the catalyst iron.

Answer: Option D. -> Its aqueous solution turns red litmus blue
The main use of litmus is to test whether a solution is acidic or basic. For instance, ammonia gas, which is alkaline, colours the red litmus paper blue.

Answer: Option B. -> Diamond
Carbon atoms in diamond are quaternary in nature. The crystal structure of a diamond is a face-centered cubic or FCC lattice. Each carbon atom joins four other carbon atoms in regular tetrahedrons (triangular prisms). Based on the cubic form and its highly symmetrical arrangement of atoms, diamond crystals can develop into several different shapes, known as ‘crystal habits’.

Answer: Option A. -> Ammonia
Ammonia gas that dissolves in water forms a solution of ammonium hydroxide (NH4OH). This solution (including the gas) is a strong base and will make the solution alkaline.