Question Discussion & Solution

The correct answer is option 2, i.e. Penicillin.

• Alexander Fleming was a Scottish microbiologist, physician, and pharmacologist who discovered the first antibiotic substance, Penicillin G from Penicillium notatum in 1928.
  • For this discovery, he received the Nobel Prize in Physiology or Medicine in 1945 along with Ernst Boris Chain and Howard Florey.
• The cell was discovered by Robert Hooke.
• Nucleus was discovered by Ernest Rutherford.
• DNA structure was discovered by Watson and Crick.

The correct answer is Amlanand Ghosh.

Key Points

• Prof Amlanand Ghosh excavated the Kalibangan site in 1952.
• The Kalibangan civilization is supposed to older than 4000 BC.
• This Rajasthan civilization was the first metropolis state in India.
• Kalibangan lies along with the left Bank of the dried-up bed of river Ghaggar.
• The site contains both pre-Harappan and Harappan remains, and therein can be seen the transition between the two cultures.
• Although the pre-Harappan culture worked copper and produced pottery, it had no writing system, and its ruins lack the orderly layout and use of baked brick that is found in the later Harappan sites.
• The Harappan remains include a cemetery and a fortified citadel. 

Additional Information

• Ratna Chandra Agrawal: 
  • Bhinmal Civilization was first founded by Ratna Chandra Agrawal in 1953-54 AD.
  • Bhinmal civilization is founded in the Jalore District of Rajasthan.
• Ratan Lal Mishra: 
  • Ganeshwar civilization was first founded in 1977 by historian Ratan Lal Mishra.
  • This Ganeshwar civilization is more than 4000 years old and the estimated time period was 2500 – 2000 BC.

• Power: The rate of work done by the electric energy is called power. It is denoted by P.
  • The SI unit of power is the watt (W).
  • Watt is a small unit that's why kilowatt-hour is used as the unit for electrical energy.
• 1 unit of electric energy: When one-kilowatt load works for 1 hour then the energy consumed is called 1 unit of electricity.

1 Unit of electricity = 1 kWh = 1000 Watt-hour = 3.6 × 106 J

1 Kilo-watt = 1000 Watt

• 1 Watt: The energy consumption rate of 1 joule per second is called 1 watt.

EXPLANATION:

Since 1 hr = 3600 sec

1 kWh = 1000 W-hr = 1000 × 3600 watt sec = 3.6 × 10⁶ J 

​So option 1 is correct.

The correct answer is Copper and Tin.
Key Points

• Bronze
  • Bronze is an alloy traditionally composed of copper and tin.
  • Bronze is of exceptional historical interest and still finds wide applications.
  • It was made before 3000 BC, though its use in artifacts did not become common until much later.
  • The proportions of copper and tin varied widely (from 67 to 95 percent copper in surviving artifacts), but, by the Middle Ages in Europe, certain proportions were known to yield specific properties.
  • An alloy described in an 11th-century Greek manuscript in the library of St. Mark’s, Venice, cites a proportion of one pound copper to two ounces of tin (8 to 1), approximately that used for bronze gunmetal in later times.
  • Some modern bronzes contain no tin at all, substituting other metals such as aluminum, manganese, and even zinc.

Additional Information

• Copper and Silver
  • The best-known copper-silver alloy is sterling, which is 92.5 percent silver and 7.5 percent copper.
  • In England sterling, silver is traditionally identified by the hallmark of a lion passant.
  • Coin silver is an alloy of 90 percent silver and 10 percent copper.
  • For jewelry and ornaments, 85–90 percent silver (and the balance copper) is frequently used.
  • Dental alloys of 60–70 percent silver, 18–25 percent tin, 2–14 percent copper, and 0.5–2 percent zinc are amalgamated with varying quantities of mercury to form the filling materials for cavities in teeth.
• Copper and zinc
  • Brass is an alloy of copper and zinc, of historical and enduring importance because of its hardness and workability.
  • The earliest brass was called calamine brass, which dates to Neolithic times.
  • It was probably made by the reduction of mixtures of zinc ores and copper ores.
  • In ancient documents, such as the Bible, the term brass is often used to denote bronze, the alloy of copper with tin.
• Copper and Lead
  • Leaded bronzes contain from 4 to 25 percent lead plus additions of copper and tin, and some copper-lead bearing alloys contain up to 40 percent lead.
  • All these bearing alloys are sufficiently soft so that lubrication failure does not result in damage to the bearing.
  • Lead-based bearing alloys are also known as lead-based babbitt metals or white metals.
  • These are usually antimonial lead with widely variable additions of tin or copper (or both) and arsenic to increase strength.
  • One such alloy is commonly used for railroad-car journal bearings, contains 86 percent lead, 9 percent antimony, and 5 percent tin.
  • Many alloys of lead and alkaline-earth metals, such as calcium and sodium, also are widely used as bearing materials.