Question Discussion & Solution

Given : Cobbler : Shoes – Cobbler mends our shoes.

Electrician : Screw – Screw is a tool used by electricians.

Carpenter : Jig – Jig is a tool used by carpenters.

Mechanic : Car – Mechanic mends our cars.

Manager : Office – Manager is a superior person who handles the administrative work of an office.

The correct answer is Soap solution is alkaline.

Concept:

• Indicators are the substances that are used to identify whether the given substance is an acid or a base.
• There are two types of indicators:
  • Natural: These indicators are obtained from natural sources like plants. 
  • Turmeric, litmus, china rose petals, etc., are some of the naturally occurring indicators.
  • The most commonly used natural indicator is litmus.
  • It is extracted from lichens.
  • It is available in the form of a solution, or in the form of strips of paper, known as litmus paper.
  • Generally, it is available as red and blue litmus paper.
  • Man-made: Phenolphthalein, Methyl orange are some of the man-made indicators.

Explanation:

• • The indicators change their colour when added to a solution containing an acidic or a basic substance.
  • Turmeric is a natural indicator. It contains the substance

curcumin which changes colour with pH.

• When a substance is basic, the colour is red, whereas when the substance is acidic, the colour of turmeric turns yellow to brown

• Turmeric stains on the shirt turn red when washed with soap because the soap solution is basic in nature which changes the yellow colour of Turmeric into red colour.
• It is because turmeric contains tartaric acid, while the soap contains a sodium hydroxide base. When an acid reacts with a base, a neutralization reaction takes place and the stain becomes neutral.

Neutralization Reaction

• A neutralization reaction can be defined as a chemical reaction in which an acid and base quantitatively react together to form salt and water as products.

Saponification

• Saponification is the hydrolysis of an ester with NaOH or KOH to give alcohol and sodium or potassium salt of the acid.

The correct answer is Interconnection and networks.

Key Points

• Internet:
  • The term Internet is derived from the words interconnection and networks. Hence, Option 4 is correct.
  • The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices.
  • It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies.
  • The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing. 
  • The first web page address was http://info.cern.ch/hypertext/WWW/TheProject.html.
  • ARPANET adopted TCP/IP on January 1, 1983.
  • NCSA Mosaic ran on Windows computers was the first browser to surf the internet. 

Additional Information

• A computer network is mainly of four types:
  • LAN(Local Area Network)
  • PAN(Personal Area Network)
  • MAN(Metropolitan Area Network)
  • WAN(Wide Area Network) 

Flood is overflow of water. In the same way, drought is a continuous dry period of weather.

Bleaching powder:

• Calcium hypochlorite is known as bleaching powder.​
• It is a pale yellowish powder having a strong smell of chlorine.
• It is soluble in cold water.
• Bleaching powder reacts with dilute acids to produce chlorine.
• When bleaching powder is treated with an excess of a dilute, all the chlorine present in it is liberated.
• It is used in bleaching clothes in the laundry due to its oxidizing property.

Formula- CaOCl₂ 

Additional Information

• Washing powder: The chemical name of washing soda is Sodium carbonate Decahydrate and the chemical formulae is Na_2​CO3​.10H_2​O.
• Baking powder: Sodium hydrogen carbonate is the chemical term for the baking powder with chemical formulae NaHCO₃.
• Soda ash: Anhydrous Sodium carbonate is known as Soda ash with chemical formulae Na₂CO₃.