Daily Quiz: UPSC Prelims Marathon – March 15, 2018

Statement 1 is correct. Hydrogen bombs, or thermonuclear bombs, are more powerful than atomic or “fission” bombs. The difference between thermonuclear bombs and fission bombs begins at the atomic level.

Statement 2 is correct. Nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high energy and fuse together into a new nucleus, e.g. helium.

Statement 1 is correct. Graphene is the thinnest compound known to man at one atom thick (a million times thinner than a human hair), the strongest compound discovered (between 100-300 times stronger than steel), the lightest material known (with one square meter weighing approximately 0.77 milligrams),and extremely flexible.

Statement 2 is correct. Graphene is impermeable to molecules, and is highly electrically and thermally conductive – graphene enables electrons to flow much faster than silicon. It is also a transparent conductor, combining electrical and optical functionalities in an exceptional way.

Pair 3 is incorrectly matched.

Phosphoric acid (H3PO4) is used as a rust remover: Phosphoric acid acts as a rust converter, converting the ferric oxide (Fe2O3) to ferric phosphate (FePO4), which can then be easily scrubbed off. Phosphoric acid for this purpose is commonly sold as a gel called naval jelly.

Chlorine (Cl2): Chlorine has many uses, including the following:

To produce consumer and industrial products such as plastics, pharmaceuticals, dyes, household cleaners (including bleach and other disinfecting agents), insecticides, and textiles

To treat water in multiple ways:

To largely eliminate waterborne pathogens during water purification in water treatment plants in the United States

To kill bacteria in swimming pools; sodium hypochlorite produced from chlorine is used

To act as a major reactant in the production of bulletproof vests, computer chips, and auto parts

Statements 1 and 2 are correct.

When light travels from an optically denser medium to a rarer medium at the interface, it is partly reflected back into the same medium and partly reflected to the second medium. If the angle of incidence is greater than the critical angle refraction is not possible, and the incident ray is totally reflected. This is called Total Internal Reflection.

Statement 1 is incorrect. A fuel cell produces electricity through a chemical reaction, but without combustion. It converts hydrogen and oxygen into water, and in the process also creates electricity. It’s an electro-chemical energy conversion device that produces electricity, water, and heat.

Statement 2 is correct. Hydrogen fuel cells only produce heat and water – no toxins, particles, or greenhouse gasses, which means clearner air for us to breathe.

A photovoltaic cell (PV cell) is a specialized semiconductor diode that converts visible light into direct current (DC). Some PV cells can also convert infrared (IR) or ultraviolet (UV) radiation into DC electricity. Photovoltaic cells are an integral part of solar-electric energy systems, which are becoming increasingly important as alternative sources of utility power.

The diopter is the unit of measure for the refractive power of a lens.