Question Discussion & Solution

Letters are replaced by their place values as in the general alphabetical series.

Similarly,

Hence, answer is '14935'.

CONCEPT:

Nuclear reactor:

• It is a device in which a nuclear reaction is initiated, maintained, and controlled.
• It works on the principle of controlled chain reaction and provides energy at a constant rate.

EXPLANATION:

• Nuclear Fuel: It is a fissionable material to be used for the fission process to take place. Therefore option 1 is correct.
• Commonly used fuels in a nuclear reactor are U233, Enriched U235, Pu239 etc. 
• Generally, uranium oxide pellets are inserted end to end into long hollow metal tubes constituting the fuel rods.
• When slow neutrons interact with the fuel, the fission starts, and the energy is released. 

Additional Information

• The moderator's function is to slow down the fast-moving secondary neutrons produced during the fission.
  • The material of the moderator should be light and it should not absorb neutrons.
  • Usually, heavy water, graphite, deuterium, and paraffin, etc. can act as moderators.
• Controller: These are made with neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it. 
• Lubricant: Lubricant has shown that it is possible to produce materials capable of lubricating some reactor components.
  • In order to further the development of such lubricants, the U.K.A.E.A. and the nuclear manufacturing groups have co-operated in providing lubricant manufacturers.

The correct answer is Silver.

Key Points

• Gold
  • It is one of the softest metals, and this quality makes it easier to design it in various jewelry designs.
  • It is tough making 24 karat gold jewelry. Other metals have to be added to it to increase its durability and strength.
  • If you wish to know what is 24 karat gold, you must understand that 24 karat gold is the purest form of this yellow metal.
  • Although 24 karat is pure gold, a jewelry piece made up of this purity is not solid and flexible enough.
  • When creating and crafting beautiful, intricately designed, and patterned gold jewelry, the metal needs to be added with other alloys to lend it the necessary strength.
  • The metals usually added to gold metal are zinc, nickel, silver, copper, etc. Hence, Option 3 is correct.
  • This is because when gold melts its state will change into a liquid.
  • Gold will like water so it flows and it will become difficult to mold.
  • So copper is added to gold which is there in the liquid state, so it will harden gold a little bit to prevent it from flowing which will be easy to mold gold to make ornaments.

Important Points

• Silver
  • It is a chemical element with the symbol Ag and atomic number 47.
  • A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.

Additional Information

• Zinc
  • It is a chemical element with the symbol Zn and atomic number 30.
  • Zinc is a slightly brittle metal at room temperature and has a silvery-greyish appearance when oxidation is removed.
  • It is the first element in group 12 of the periodic table.
• Lead
  • It is a chemical element with the symbol Pb and atomic number 82.
  • It is a heavy metal that is denser than most common materials.
  • Lead is soft and malleable, and also has a relatively low melting point.
  • When freshly cut, lead is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air.
• Tin
  • It is a chemical element with the symbol Sn and the atomic number 50.
  • Tin is a silvery metal that characteristically has a faint yellow hue.
  • Tin is soft enough to be cut with little force.

The pattern followed here is:

25 → First digit of 23 and second digit of 65.

68 → First digit of 61 and second digit of 38.

? → First digit of 72 and second digit of 48 → 78.

Hence, the answer is 78.

The correct answer is Yamuna River System.

Key Points

• The Betwa is a tributary of the Yamuna River.
• It originates in the Vindhya Range in Madhya Pradesh and flows through Orchha (Madhya Pradesh) before reaching Uttar Pradesh.
• It joins the Yamuna River near Hamirpur after traveling 590 kilometers.
• The Betwa River has two major tributaries: the Halali and Dhasan Rivers.
• The Yamuna river is a major tributary of the river Ganges, it originates from the Yamunotri glacier near the Banderpoonch peaks of the lower Himalayas.
• It travels a total length of 1,376 kilometers and merges with the Ganges at Triveni Sangam, Prayagraj (Allahabad).
• Tons, Hindon, Ken, Betwa, Chambal rivers are some of its tributaries.

Additional Information

• Ganga River System:
  • The Ganga (the Padma in Bangladesh) forms by the confluence of Alakhnanda and Bhagirathi at Devprayag.
  • Bhagirathi originates from Gangotri glacier and Alakhnanda originates from Satopanth glacier.
  • The total length of the Ganga river is 2525 km.
  • Some of the tributaries of Ganga are the Yamuna, the Ramganga, the Gomati, the Ghaghara, the Gandak, the Kosi and the Mahanada.
• Narmada:
  • The Narmada is the largest west-flowing river in India.
  • It rises near the Amarkantak range of mountains in Madhya Pradesh.
  • It is the fifth-largest river in the country.
  • The total length of the river is 1312 kilometers.
  • The Sher, the Dudhi, the Tawa (biggest tributary), the Ganjal, the Hiran, the Barna, the Choral, and the Lohar are some of the tributaries of the Narmada river.
• Tapti:
  • Tapti River is one of the major rivers of peninsular India.
  • Its total length is 724 km.
  • The Tapti river source of origin lies in Multai, in the Betul district of Madhya Pradesh.
  • Vaki, Gomai, Arunavati, Aner, Panjhra, Bori, and Girna are some of the tributaries.