Because it works as a hardening agent. So, basically the impurity of Carbon in Iron stops the dislocation of the Iron atoms in the lattice from sliding past one another. The amount of this impurity is used to control the hardness, ductility and tensile strength.

• The Steel which has Carbon as alloy is called "Carbon Steel". The Steel which has Non-carbon alloy is called "Alloy Steel".
• The iron which was used in earlier times using techniques in crucible is called "Crucible Steel". In India, Konasamudram and Gatihosahalli were the most important sources of Crucible Steel till 16th century.
• The immediate product of the Iron alloy found in mines is "Pig iron". Pig Iron has a very high Carbon Content (3.5-4.5%). So it is Brittle, Non-malleable and used only in limited applications.
• Iron alloy which has impurity more than 2.1% but less than the Pig Iron is called "Cast Iron". They are mostly brittle but there are Malleable Cast Irons. The Cast Iron because of more impurities has a lower melting point.
• Historically cast Iron has been used in "Bridge making" all over the word. The famous "Iron Bridge" of England is made up of Cast Iron.
• "Wrought iron" has very low carbon content. It is also known as "Slag'. When it is bent to the point of breaking, it gives texture which resembles wood.
• Wrought Iron was earlier known as "Pure Iron", but not now because; now the Iron, which has less than 0.008% impurity iss considered to be commercially pure. The "Eiffel Tower " is made up of Wrought Iron.
• Following table compares the Pig Iron, Carbon Steel and Wrought Iron.

The Age of the Moon predicted to ~ 4.36 Billion Years

• Scientists claimed that the Age of the moon: ~ 4.36 billion years, i.e. nearly 200 million years less than what earlier predicted. Thus, the moon could be younger than earlier thought, as per the Scientists.

• Existing Theory: The existing theory of the moon's origin is that it was formed by a massive impact b/w a big planet-like object and Earth. The energy of the impact was satisfactorily high that the moon formed from melted material that was expelled into space. As the moon cooled, this magma solidified into different mineral components.

• New Theory: Now detailed analysis of lunar rock samples thought to have been derived from the original magma has given scientists a new estimate of the moon's age at ~4.36billion years.

    As per this theory for lunar formation, a rock type called "ferroan anorthosite" or FAN - is the     oldest of the moon's crustal rocks, but scientists have had difficulty dating FAN samples.

• The Research team analyzed the isotopes of the elements lead and neodymium to place the FAN sample's age at 4.36 billion years. This figure is significantly younger than earlier estimates of the Moon's age that range as old as the age of the solar system at 4.568billion years.
• The new, younger age obtained for the oldest lunar crust is similar to ages obtained for the oldest terrestrial minerals - zircons from Western Australia - suggesting that the oldest crusts on both Earth and moon formed at about the same time, and that this time dates from shortly after the giant impact.
  
• The study is the first in which a single sample of FAN yielded consistent ages from multiple isotope dating techniques.
• The result strongly suggests that these ages pinpoint the time at which the sample crystallized.
• The extraordinarily young age of this lunar sample either means that the moon solidified significantly later than previous estimates, or that we need to change our entire understanding of the Moon's geochemical history.
  
• The research team, led by Lars Borg of the Lawrence Livermore National Laboratory in California, used newly refined techniques to determine the age of a sample of FAN from the lunar rock collection at the Nasa Johnson Space Centre.
• The results are published in the journal Nature.

Correct answer of this question is 1, 2, 3 & 4.

Recently, the Haryana Power Generation Corporation Limited (HPGCL) had offered two sites to the Nuclear Power Corporation of India Limited (NPCIL) for setting up a second nuclear power plant in the State The locations are Balsamand area of Hisar and Kitlana-Nimiriwali-Ajitpur area of Bhiwani. Now the NPCIL team will during the visit collect certain details regarding the availability of water, cropping patterns, power evacuation arrangements and the distance from the nearest railway head in order to proceed further.

The options mentioned in question are discussed as follows:

• Seismcity: If the area of a nuclear site is seismically active, it may not be used for Nuclear Power Plant, the reasons are obvious.
  • Now here we must note that the controversial Jaitapur Plant is located in Zone II of seismic map of India and NOT considred to be seismically active region.
• Water Availability: The nuclear power plants would need a lot of water also for power production. So this criterion must be taken into account.
• Economic Activities: The Economic Activities of the area MUST be taken care of. Here, I would quote an example of the Three Mile Island accident of United States that happened in 1979.
  • Three Mile Island Nuclear Generating Station is located in the state of Pennsylvania in United States. In 1979, there was a core meltdown in one of the units of a pressurized water reactor.
  • This resulted in release of approximately 2.5 million curies of radioactive gases, and approximately 15 curies of iodine-131.
  • Now, after that incident, a new criteria of site selection was introduced in the United States. As per these new criteria, since the nuclear reactor accompanies the local infrastructure and economic development also, there should be a security zone around the plant, so that it is ensure that in case of such accident, the population can be evacuated. The moral of the story is that the area nearby the nuclear plant must NOT be overdeveloped.
  • Distance from the Railway Station: This is also needed, as the construction of plant would need a lot of logistic support.

The Resourcesat was launched  via the PSLV C-16 on 20.4.2011 . Resourceset-2 will be able to collect data from a wider strip of the Earth’s surface in comparision to Resourcesat I. The profile page of Resourcesat-2 on ISRO website mentions that Important changes in RESOURCESAT-2 compared to RESOURCESAT-1 are: Enhancement of LISS-4 multispectral swath from 23 km to 70 km and improved Radiometric accuracy from 7 bits to 10 bits for LISS-3 and LISS-4 and 10 bits to 12 bits for AWIFS. Besides, suitable changes, including miniaturization in payload electronics, have been made in RESOURCESAT-2.
The Swath width means the strip of the Earth’s surface from which data are collected by a satellite.Both Resourcesat-1 and Resourceset -2 will provide remote sensing data services for entire globe. The Resourcesat-2 has been launched with additional payload known as AIS (Automatic Identification System) from COMDEV, Canada as an experimental payload for ship surveillance in VHF band. PSLV C-16 has launched RESOURCESAT-2 satellite, the joint Indo-Russian YOUTHSAT satellite, and Singapore's first satellite X-SAT. Resourcesat-2 is India's 18th remote sensing satellite.

There are five biofertilizers viz. Rhizobium, Azotobacter, Azospirillum, Phosphate Solubilizing Bacteria and mycorrhiza , which have been incorporated in India's  Fertilizer Control Order (FCO), 1985.  Rhizobium, Azotobacter, Azospirillum and blue green algae(BGA) have been traditionally used as Biofertilizers. Rhizobiuminoculant is used for leguminous crops such as pulses. Azotobacter can be used with crops like wheat, maize, mustard, cotton, potato and other vegetable crops. Blue green algae such as Nostoc, Anabaena, Tolypothrix and Aulosira fix atmospheric nitrogen and are used as inoculants for paddy crop.  Phosphate solubilizing bacteria like Pantoea agglomerans strain P5, and Pseudomonas putida strain P13 are able to make the phosphate usable by solubilize it from inorganic sources.