Question Discussion & Solution

• Dioptre is the S.I. Unit of Power of a lens.
• A dioptre is equal to the reciprocal of the focal length measured in metres.
• Power of a lens is the ability of a lens to converge or diverge light rays depending on its focal length.

Option(3) is correct.

Assumption I: There is a doubt about the quality of water being supplied in the town: Cholera is spread through water or through food and to prevent the spread of cholera in town, doubt about the quality of water is precautionary. So, this assumption is implicit.

Assumption II: There is some report of cholera in town: As indicated in the given statement, the medical department attempt to prevent the spread of cholera and the spreading of disease only takes place if it exists. So, this assumption is implicit.

Hence, the correct answer is an option(3)i.e., Both the assumptions are correct.

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 Dial-up.

Key Points

• Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialling a telephone number on a conventional telephone line.
• Dial-up connections use modems to decode audio signals into data to send to a router or computer and to encode signals from the latter two devices to send to another modem. 
• It is considered the slowest internet service among all.

Additional Information

• In 1979, Tom Truscott and Steve Bellovin, graduates of Duke University, created an early predecessor to dial-up Internet access called the USENET. 
• 5G can be significantly faster than 4G, delivering up to 20 Gigabits-per-second (Gbps) peak data rates and 100+ Megabits-per-second (Mbps) average data rates.
• 5G is considered the fastest internet service till now.

The correct answer is Save As.

Key Points

Save and Save As are the two options for saving a file in Word.

• These choices operate in a similar manner, with a few key distinctions.

Save:

• You'll use the Save command to save your changes when you're creating or editing a document.
• The majority of the time, you'll use this command.
• You'll only have to specify a file name and location the first time you save a file.
• After that, you may save it with the same name and location by using the Save command.

Save As:

• Save As command will be used to make a copy of a document while maintaining the original.
• When you choose Save As, you'll need to give the cloned version a new name and/or location.

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