Question Discussion & Solution

CONCEPT:

• Ultrasonic waves are the sound waves with frequencies higher than the upper audible limit of human hearing.
  • They have a short wavelength.
• Echo: If we shout or clap near a suitable reflecting object such as a tall building or a mountain, we will hear the same sound again a little later. This sound which we hear is called an echo.
  • Echoes are heard due to the phenomenon of Reflection of sound waves.
• SONAR: It a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water
  • SONAR stands for ‘Sound Navigation and Ranging.’
  • SONAR is based on the principle of echo.
  • Sonar is often used as a measurement of acoustic location and echo characteristics of the target object in the water.
  • It sends ultrasonic waves towards the bottom area of the sea and after reflection, the sound comes to the ship. We measure the time taken by the sound wave and then we get the depth. 

EXPLANATION:​

• From the above discussion, we can say that the SONAR uses the principle of reflection of sound waves(Echo) to detect and locate objects. So option 2 is correct.
• Reverberation: The persistence of sound in a closed enclosure, due to continuous reflections at the walls or the floor or the ceiling of the enclosure, even after the source has stopped producing sound is known as 'reverberation'.

CONCEPT:

• Force: The interaction which after applying on a body changes or try to change the state of motion or state of rest is called force.
• Force is denoted by F and the SI unit is Newton (N).

• Force (F) = Mass (m) × acceleration (a)

EXPLANATION:

• Both Dyne and Newton are units of force in the CGS and S.I system.
• Newton and dyne can also be written as (1 N = kg-m/s2) and (1 dyne = gm-cm/s2).
• The relation between the Newton and  Dyne is given as 

⇒ 1 N = 105 dyne

• Therefore, the ratio of SI unit and CGS unit of force is

\(\Rightarrow \frac{N}{Dyne} = 10^5\)

Anish walked 100 m towards north.

He then took a U-turn and walked 100 m.

Now he took a U-turn again and walked 102 m.

From here he turned left and walked 93 m.

Anish facing west direction.

Hence, option 2 is the correct answer.

Explanation:

Option 1 is correct, i.e. Anthracite.

• Anthracite, also called the hard coal is a highly metamorphosed form of coal.
• The calorific value of a substance is defined as the amount of heat released by a unit weight of a substance during complete combustion.
• Anthracite coal has the highest calorific value.

Anthracite is a type of coal that has the highest carbon content.

• Anthracite: 87-96%
• Bituminous: 45-86%
• Lignite: 25 - 35%

Extra information:​

• The most common volatile matter in coal is water, carbon dioxide, and sulfur dioxide.
•  Volatile matter is directly related to coal rank; as coal rank increases, volatile matter content decreases.
• Peat has the highest volatile matter.

The Venn diagram that best represents the relationship between Uttar Pradesh, Jhansi, Goa is shown below:

Jhansi is a city of Uttar Pradesh.

Whereas, 

Uttar-Pradesh and Goa both are different States of India thus will come as a separate circle.

Hence, Option (4) is correct.

Additional InformationUttar-Pradesh:

• The Dudhwa National Park is located in Terai and is spread over an area of 490 sq.km. The national park also has the Dudhwa tiger reserve within its premises.
• National Chambal Sanctuary is also known as the National Gharial Wildlife Sanctuary that is home to the endangered gharial or small crocodile. The river Chambal follows through this sanctuary as the hills and ravines build many sandy beaches inside the park.
• Situated in the district of Pilibhit in Northern Uttar Pradesh, Pilibhit Tiger Reserve is one of the 41 Project Tiger reserves of the country. The forest cover here is dense which is why the tigers have a good eco-system to survive in with enough prey. The reserve is home to over 127 different kinds of animals and 556 kinds of birds.
• The Nawabganj bird sanctuary also popularly known as Shahid Chandra Shekhar Azad bird sanctuary is situated in the Unnao district of Uttar Pradesh. The sanctuary is famous for being the temporary home of more than 250 kinds of birds. The birds come all the way from former USSR countries.
• Chandraprabha Wildlife Sanctuary is located near the city of Varanasi, Uttar Pradesh. The sanctuary is not as famous as the other ones in the area but the place is rich in scenic landscapes and waterfalls. The two famous waterfalls are; Rajdari and Devadari. The variety of animals found here are the wild boar, Indian gazelle and blackbucks.

Goa:

• Spread over an area of 211 square kilometres, Netravali Wildlife Sanctuary is one of the newly established wildlife sanctuaries in Goa.
• With the number of Royal Bengal tigers that can be found at the Mhadei Wildlife Sanctuary, authorities are considering to promote the place as one of the Project Tiger Reserves. Among the very popular sanctuaries of Goa, it is located near Valpoi town in Sattari Taluka.
• The Bhagwan Mahaveer Sanctuary is the biggest wildlife sanctuary in Goa and is located in Sanguem taluka. It spreads over an area of 240 square kilometres. Along with the stunning landscapes of the Western Ghats, the sanctuary also encompasses the very famous Dudhsagar Falls and a number of temples from the era of the Kadamba Dynasty. You can also visit the famous Devil’s Canyon View Point, a perfect place to spot wildlife and birds.
• Set up in 1968 and spread over an area of 105 square kilometres, the Cotigao Wildlife Sanctuary is situated in the southern part of Goa, near Canacona Taluka.
• The core area of Bhagwan Mahaveer Sanctuary is known as the Molem Wildlife Sanctuary. It is located in the Sanguem region and is claimed to house up to 120 different species of birds such as drongo, golden oriole, the great Indian hornbill, three-toed kingfisher, wagtails, and fairy bluebird.