Question Discussion & Solution

The correct answer is ​Myopia.

Key Points

• Nearsightedness (myopia) is a common vision condition in which you can see objects near to you clearly, but objects farther away are blurry.
• It occurs when the shape of your eye causes light rays to bend (refract) incorrectly, focusing images in front of your retina instead of on your retina.
• A Concave lens (diverging lens) is used by people suffering from myopia.

Additional Information 

• Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred.
  • This blurred effect is due to incoming light being focused behind, instead of on, the retina wall due to insufficient accommodation by the lens.
• Night blindness is a type of vision impairment also known as nyctalopia.
  • People with night blindness experience poor vision at night or in dimly lit environments.
  • Although the term “night blindness” implies that you can't see at night, this isn't the case.
• Astigmatism: This defect arises due to the difference in the radius of curvature of the cornea in the different planes
  • The cylindrical lens is used by people suffering from Astigmatism.

The correct option is 2 i.e. Sodium Carbonate

Key Points

• Sodium Carbonate is also known as washing soda it is a salt of carbonic acid.
• Sodium carbonate can be manufactured by Solvay's process.
• It is used for treating hard water and industrial detergent mixtures.
• The aqueous solution of sodium carbonate is alkaline.
• Calcium Sulphate exists in the forms of white solids and is not soluble in water.
• Plaster of Paris and Gypsum are its hydrates.

CONCEPT:

• Power: The rate of work done is called power.
  • It is denoted by P.
  • Mathematically it is written as

\(Power\;\left( P \right) = \frac{{\;W}}{{t}}\)

CALCULATION:

Given - mass of 1^st person (m₁) = 80 kg, mass of 2^nd person (m2) = 60 kg, time (t₁) = 12 sec, and time (t2) = 11 sec​

• The power to take an object to a certain height in 12 sec by 1^st person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{80gh}{12}\)       ----(1)

• The power to take an object to a certain height in 11 sec by 2^nd person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{60gh}{11}\)       ----(2)

On dividing equations 1 and 2, we get

\(\Rightarrow \frac{P_1}{P_2} =\frac{\frac{80gh}{12}}{\frac{60gh}{11}}=\frac{11}{9}\)

The correct answer is Aravali.

• Aravali range forms the main water area for Rajasthan.

Key Points

• Aravali range​
  • The Aravallis of Northwestern India, one of the oldest fold mountains of the world, now form residual mountains with an elevation of 300m. to 900m.
  • They stretch for a distance of 800 km from Himmatnagar in Gujarat to Delhi, spanning Haryana, Rajasthan, Gujarat, and Delhi, the 692 kilometres (km).
  • The Aravallis act as a barrier between the fertile plains in the east and the sandy desert in the west.
  • Historically, it is said that the Aravalli range checked the spread of the Thar desert towards the Indo-Gangetic plains, serving as a catchment of rivers and plains.
  • Thus Aravali range forms the main water area for Rajasthan.

​Additional Information

•  Aravali range formation
  • ​These are fold mountains of which rocks are formed primarily of the folded crust when two convergent plates move towards each other by the process called orogenic movement.
  • The Aravallis date back to millions of years when a pre-Indian sub-continent collided with the mainland Eurasian Plate.
  • Carbon dating has shown that copper and other metals mined in the ranges date back to at least the 5th century BC.