Q: Which of the following is a communicable disease?

A: Measles

B: Scurvy

C: Asthma

D: Diabetes



Correct Option: A  [ Measles ]

Remark:

Explanation: Measles is a highly contagious viral disease caused by the measles virus (a member of the Paramyxovirus group). It spreads through droplets released when an infected person coughs or sneezes. Symptoms include fever, cough, rash, and watery eyes. Other diseases listed — scurvy, asthma, and diabetes — are non-communicable as they do not spread from person to person.


Q: Ozone hole refers to :

A: hole in Ozone layer

B: decrease in the Ozone layer

C: decrease in thickness of Ozone layer

D: increase in thickness of Ozone layer



Correct Option: C  [ decrease in thickness of Ozone layer ]

Remark:

Explanation: The term "Ozone hole" does not mean an actual hole but refers to a significant decrease in the thickness of the ozone layer in the Earth's stratosphere. This thinning occurs mainly over the Antarctic region during spring (September–November) due to chemical reactions involving chlorofluorocarbons (CFCs) and other ozone-depleting substances. These chemicals release chlorine and bromine atoms, which destroy ozone (O₃) molecules. The thinning allows more harmful ultraviolet (UV) radiation to reach the Earth's surface, causing health and environmental hazards.


Q: Noise levels in residential areas should not exceed:

A: 30 decibels

B: 100 decibels

C: 85 decibels

D: 55 decibels



Correct Option: D  [ 55 decibels ]

Remark:

Explanation: The permissible noise level in residential areas should not exceed 55 decibels (dB) during the daytime and 45 dB at night, as per the Central Pollution Control Board (CPCB) guidelines. Exposure to higher noise levels can lead to stress, disturbed sleep, and hearing impairment.


Q: Lens is made up of:

A: pyrex glass

B: flint glass

C: ordinary glass

D: cobalt glass



Correct Option: B  [ flint glass ]

Remark:

Explanation: A lens is generally made of flint glass, which contains lead oxide. Flint glass has a higher refractive index than ordinary glass, allowing it to bend light more effectively. This property makes it ideal for manufacturing optical instruments such as lenses and prisms.


Q: What is common in AIDS, hepatitis and typhoid fever ?

A: All are bacterial disease

B: All are water borne diseases

C: All are viral disease

D: All are spread by human beings



Correct Option: D  [ All are spread by human beings ]

Remark:

Explanation: AIDS, Hepatitis, and Typhoid fever are all diseases that can be spread by human beings. While AIDS and Hepatitis are viral diseases and Typhoid is a bacterial disease, all three are transmitted through contact with infected individuals or their body fluids, making human-to-human transmission common.


Q: A fuse wire has :

A: high resistance and high melting point

B: low resistance and high melting point

C: low resistance and low melting point

D: high resistance and low melting point



Correct Option: D  [ high resistance and low melting point ]

Remark:

A fuse wire has high resistance and a low melting point. It is made of materials like tin-lead alloy so that it melts quickly when excessive current flows through the circuit. This breaks the circuit and prevents damage to electrical appliances due to overheating or short circuits.

  • High resistance: Causes heating when excess current passes.
  • Low melting point: Ensures the fuse melts easily to interrupt the circuit.


Q: Average distance of the earth from the Sun is:

A: 150 Million km

B: 15 Million km

C: 90 Million km

D: 900 Million km



Correct Option: A  [ 150 Million km ]

Remark:

The average distance between the Earth and the Sun is approximately 150 million kilometers (or about 1 Astronomical Unit – 1 AU). This distance serves as a standard unit of measurement for describing distances within our solar system. Despite slight variations due to Earth's elliptical orbit, this average remains nearly constant and is crucial for maintaining suitable conditions for life on Earth.

Other options (for context)

  • 15 Million km: Far too close — the Earth would be extremely hot and uninhabitable.
  • 90 Million km: Shorter than the actual average distance.
  • 900 Million km: Much greater — about six times the real distance, closer to Saturn’s orbit.


Q: The primary producer in an ecosystem are:

A: Bacteria

B: Women

C: Men

D: Plants



Correct Option: D  [ Plants ]

Remark:

Explanation: In any ecosystem, green plants (and some algae and cyanobacteria) act as primary producers. They convert solar energy into chemical energy through the process of photosynthesis, producing glucose and oxygen. This stored energy becomes the foundation of all food chains, supporting consumers and decomposers. Thus, plants form the first trophic level in an


Q: Heat transfer horizontally within the atmosphere is called:

A: conduction

B: convection

C: absorption

D: advection



Correct Option: D  [ advection ]

Remark:


Q: All enzymes are actually

A: Protein

B: Carbohydrates

C: Fatty acids

D: Steroids



Correct Option: A  [ Protein ]

Remark:

Explanation: All enzymes are proteins (except a few RNA-based enzymes called ribozymes). Enzymes act as biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They work by lowering the activation energy of reactions, ensuring that metabolic processes occur efficiently at normal body temperatures. Each enzyme is specific to a particular substrate, forming an enzyme-substrate complex to carry out its function effectively.

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