Question Discussion & Solution

The correct answer is Windows, Icons, Menus.

• In a GUI-based operating system, the graphical user interface is based on Windows, Icons, Menus.

Key Points

• A  graphical user interface(GUI) uses windows, icons, and menus to perform various commands, such as opening, deleting, and moving files.
• A GUI operating system is primarily navigated using a mouse, a keyboard can also be used via keyboard shortcuts or arrow keys. 

The correct answer is Option(2).i.e.Alpha Decay.     

• In radioactivity, the emission consists of the Helium nucleus sustains under Alpha Decay. 
• Alpha Decay: 
  • It is basically responsible for the emission of the Helium nucleus. 
  • An alpha particle is consists of two neutrons & two protons which is the same as a helium nucleus.
  • We generally use 24He to implement an alpha particle which has a 2+ charge.
  • The original atomic number of the atom decreases by two (because of the loss of two protons), and its mass number decreases by four (because of the loss of four nuclear particles) when a radioactive atom throws down an alpha particle. 
• Emission of Alpha Particle: 
  •  The emission of an alpha particle can be present with a chemical equation: 
  • For example, the alpha-particle emission of uranium-235 is as follows:
       ²³⁵U₉₂→⁴He₂ + ²³⁵Th₉₀  

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 Curvature of the lens.

Important Points

• Focal length of a lens depends on its curvature and the medium outside the lens.

Additional Information

• The ability of a lens to converge or diverge light rays depends on its focal length.
  • For example, a convex lens of short focal length bends the light rays through large angles, by focussing them closer to the optical centre.
  • Similarly, the concave lens of a very short focal length causes a higher divergence than the one with a longer focal length.
• The degree of convergence or divergence of light rays achieved by a lens is expressed in terms of its power.
  • The power of a lens is defined as the reciprocal of its focal length.

Food chain: 

• A food chain shows the feeding relationship between different organisms in a particular environment and/or habitat.
• A food chain shows how energy is passed from the sun to producers, from producers to consumers, and from consumers to decomposes such as fungi.
• They also show how animals depend on other organisms for food.
• A simplified food web illustrating a three-trophic food chain (producers-herbivores-carnivores) linked to decomposers.

Key Points

Food Web: 

• A food web is similar to a food chain, but the food web is significantly larger.
• Occasionally, a single organism is eaten by a large number of predators, or it consumes a number of other species.
• As a result, several trophic levels become intertwined, and the food chain fails to accurately depict the flow of resources.
• The food chains are very simple and hence, do not exist in reality, 
• Rather, an interconnection of many food chains is seen in nature or in our ecosystem that forms a food web.
• The energy flow is multidirectional.
• In a food web, one organism takes place at different trophic levels in different food chains (which combine to form a complex food web).
• It gives greater stability to the ecosystem.

​Thus, a group of interconnected food chains is called a food web.

Additional Information

Pyramid of Biomass:

• A biomass pyramid is a diagram that compares the biomass of different trophic levels within an ecosystem.
• It shows the mass of producers that are needed to support primary consumers, the mass of primary consumers required to support secondary consumers, and so on.