526: The major ingredient of leather is:
(a) Collagen
(b) Polymer
(c) Carbohydrate
(d) Nucleic acid
527: Despite having large reserves of coal, why does India import millions of tonnes of coal?
1. It is the policy of India to save its own coal reserves for future, and import it from other countries for the present use.
2. Most of the power plants in India are coal-based and they are not able to get sufficient supplies of coal from within the country.
3. Steel companies need large quantity of coking coal which has to be imported.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Explanation:
The Indian coal industry is the world's third largest in terms of production and fourth largest in terms of reserves. Around 70% of the total production is used for electricity generation and the remaining by the steel, cement and other heavy industries.
Despite having one of the world's largest reserves of coal, policy disputes and limited investment in technologies and mines has limited effective exploitation of India's reserves. In 2011, coal production increased just 1% while power generation capacity grew at 11%. Hence option 2 is correct.
The domestic production of coking coal has declined shine 2004, but coke production has increased steadily during the same period and hence the future of India coking coal would be imports. Indian coking coal production in 2008 was pegged at 23-million tons, slipped to 22-million tons in 2011 and 21.7-million tons was forecast at best in 2013. This compared with steel production of 55-million tons in 2008, which rose to 65-million tons in 2011. Hence option 3 is also correct.
528: A free-floating astronaut A pushes another free-floating astronaut B in space. The mass of A is greater than that of B. The force exerted by the astronaut A on the astronaut B will be:
(a) Equal to zero.
(b) Equal to the force exerted by B on A.
(c) Greater than the force exerted by B on A.
(d) Less than the force exerted by B on A
529: Who of the following scientists proved that the stars with mass less than 1.44 times the mass of the Sun end up as White Dwarfs when they die?
(a) Edwin Hubble
(b) S. Chandrashekhar
(c) Steven Weinberg
(d) Stephen Hawking
Explanation:
The Chandrasekhar limit limits the mass of bodies made from electron-degenerate matter, a dense form of matter which consists of nuclei immersed il+ a gas of electrons. The limit is the maximum non-rotating mass which can be supported against gravitational collapse by electron degeneracy pressure. It is named after the astro-physicist Subrahmanyam Chandrashekhar, and is commonly given as being about 1.4 solar masses. As white dwarfs are composed of electron degenerate matter no non-rotating white dwarf can be heavier than the Chandrasekhar limit. Chandrasekhar's insight into degeneracy pressure finally explained how white dwarfs could exist, and it was this work that persuaded the Nobel Committee to award him the Nobel Prize in physics in 1983,the prize being shared with Willy Fowler.
530: Assertion (A): The main constituent of the Liquefied Petroleum Gas is methane.
Reason (R): Methane can be used directly for burning in homes and factories where it cab be supplied through pipelines.
(a) Both A and R are individually true and R is the correct explanation of A.
(b) Both A and R are individually true but R is not the correct explanation of A
(c) A is true but R is false.
(d) A is false but R is true.
Explanation:
The main constituents of LPG are butane and propane. Methane can be used directly for burning in homes (biogas) and factories where it can be supplied through pipelines (CNG).