Question Discussion & Solution

Explanation:

• Bronze is an alloy of copper and tin as the two main constituent elements.
• Bronze is a copper-based alloy that typically consists of approximately 88% copper and 12% tin.
• Some other elements added in minute quantities can be aluminium, nickel or zinc.
• It is one of the first alloys used by mankind and an entire era known as the 'Bronze Age' is known because of the extensive use of the alloy in many human artefacts.

Additional Information

Steel: 

• Stainless steel is an alloy of iron and chromium.
• Steel is an alloy of iron and carbon.
• Stainless steels are steels containing at least 10.5% chromium, less than 1.2% carbon, and other alloying elements.

Solder:

• Soldering is a joining process used to join different types of metals together having different properties. 
• Solder is a metal alloy, usually made up of tin and lead which is melted using a hot iron (soldering iron).
• The iron is heated to temperatures above 600˚F which then cools to create a strong bond.
• Flux material used in soldering is ZnCl2 (Zinc Chloride) and NH4Cl (Ammonium Chloride).

Brass:

• Brass is a metal alloy that is made up of copper and zinc.
• The proportions of zinc and copper can vary to create different types of brasses with different properties.
• It has higher malleability than bronze or zinc and has a relatively low melting point (900 to 940 °C).

Mistake Points

• Copper was the first metal used by men.
• Copper was first used by man over 10,000 years ago.  
• Probably copper can be found as a naturally occurring native metal that is sometimes found in large lumps on the ground.
• People learned to make this into copper tools and other things, although, for a metal, it is quite soft.
• When it was melted over the fire, people learned how to make an alloy called bronze, which is much harder and stronger than copper.

The correct answer is Generation.

• The letter 'G' has been used for Generation in 4G technology in mobile communication.

Key Points

• Meaning of 'G' in mobile signal
  • The G in 2G, 3G and 4G stands for Generation, and they refer to the 2nd, 3rd and 4th generation of wireless technology. 
  • The higher the generation the better, fast, and powerful will be the network.
  • Letter G stands for GPRS (General Packet Radio Service).
  • It indicates the slowest speed of internet data transfer on our mobile phone.

​Additional Information

• Meaning of 'E' in mobile signal
  • Letter E stands for EDGE (Enhanced Data Rates for GSM Evolution).
  • It is also called Enhanced GPRS.
  • This technology lies somewhere in between 2G and 3G technology.
  • So, some people refer to it as 2.5G.

Explanation:

• Pulses are considered to be nitrogen-fixing crops as they have root nodules onto which symbiotic nitrogen-fixing bacteria like Rhizobium get attached and fix atmospheric nitrogen
• Whereas, Cereals are the crops that demand a lot of nitrogen thus after harvest the soil becomes deficient in nitrogen, so to compensate for this deficiency a pulse crop is grown between two cereal crops
• This practice of growing different food crops alternatively in the same field is called Crop Rotation

Important Points 

Crop Rotation

• Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons
• It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant pests and weeds.
• Crop rotation involves planting a sequence of different kinds of crops in a location over a number of seasons.
• Rotating crops helps maintain or improve soil health and maintain or increase the productivity of the farm over time
• A diverse crop rotation gives the soil microbes different food sources, which ultimately makes soil healthier.

The correct answer is ALGORITHM.

Key Points

• An algorithm is a specific procedure for solving a well-defined computational problem.
• The development and analysis of algorithms are fundamental to all aspects of Computer Science like AI, databases, graphics, networking, OS, etc.
• Algorithm development is more than just programming.
  • It requires an understanding of the alternatives available for solving a computational problem.
  • It includes the hardware, networking, programming language, and performance constraints that accompany any particular solution.

Additional Information

• An official language comprising a collection of instructions that produce different kinds of output is a programming language.
• In computer science, programming languages are used to implement algorithms.
• Most of the languages of programming consist of computer instructions.

The correct answer is Boy pushing wall in a room.

Key Points

• Boy pushing the wall in the room is not an example of work done.
  • When a boy pushes a wall, he is applying force on the wall. We see that the wall shows no displacement.
  • Work is given as the product of the forces and the displacement in the same direction.
  • Hence the work done is zero.

Additional Information

• Work is done when a force moves. Everyday examples of work include walking up a flight of stairs, lifting heavy objects, pulling a sled and pushing a shopping trolley, Applying pressure on a pebble lying on the surface, raising a book to a height.
  • Work is not done when holding a bag stationary or a book at arm's length because although a force is being applied, the force does not move.