Q: What does the term Dolby B or Dolby C printed on tape recorders and other sound systems refer to?

A: frequency modulated system

B: amplitude modulated system

C: noise reduction circuit

D: both DC and AC power can be used



Correct Option: C  [ noise reduction circuit ]

Remark:

Explanation: The terms Dolby B and Dolby C refer to noise reduction circuits used in tape recorders and sound systems. These technologies reduce background hiss and unwanted noise during playback and recording, thereby improving the overall sound quality.


Q: The largest gland of human body is :

A: Thyroid

B: Kidney

C: Pancreas

D: Liver



Correct Option: D  [ Liver ]

Remark:

Explanation: The liver is the largest gland in the human body. It is located in the upper right part of the abdomen, just below the diaphragm. The liver performs multiple vital functions, including the secretion of bile (which helps in digestion of fats), detoxification of harmful substances, storage of glycogen (energy reserve), and the synthesis of proteins and cholesterol. It also plays a crucial role in regulating blood sugar levels and metabolism. The average adult human liver weighs about 1.2 to 1.5 kilograms.


Q: A device that is responsible for changing the voltage is:

A: Transformer

B: Encoder

C: Decoder

D: Translator



Correct Option: A  [ Transformer ]

Remark:


Q: The waves which can propagate even through the vacuum,are called __________.

A: Mechanical waves

B: Reverse waves

C: Inverted waves

D: Electromagnetic waves



Correct Option: D  [ Electromagnetic waves ]

Remark:

Explanation: Electromagnetic waves can propagate even through a vacuum because they do not require any material medium for transmission. Examples include light waves, radio waves, X-rays, and microwaves. In contrast, mechanical waves like sound require a medium such as air, water, or solids to travel.


Q: One kilometre is equal to how many miles?

A: 0.84

B: 0.5

C: 1.6

D: 0.62



Correct Option: D  [ 0.62 ]

Remark:


Q: Which one of the following is a chemical change ?

A: Burning of candle

B: Melting of wax

C: Vapourisation of water

D: Magnetising of Iron



Correct Option: A  [ Burning of candle ]

Remark:

Explanation: The burning of a candle is a chemical change because new substances such as carbon dioxide, water vapour, and heat energy are produced during the reaction between wax and oxygen. This change is irreversible and results in a permanent alteration of the chemical composition of the material. In contrast, melting of wax and vapourisation of water are physical changes since no new substances are formed and the process can be reversed by cooling.


Q: What is the meaning of the word 'Tsunami' in Japanese?

A: High waves

B: Destructive waves

C: Harbour waves

D: none of these



Correct Option: C  [ Harbour wave ]

Remark:
Indian Ocean Tsunami occurred on 26 December, 2004 with an epicentre off the west coast of Sumatra, Indonesia.


Q: In which direction a rainbow is formed ?

A: Above the sun

B: Below the sun

C: Opposite to the sun

D: At the level of the sun



Correct Option: C  [ Opposite to the sun ]

Remark:

Explanation: A rainbow is formed in the part of the sky opposite to the Sun. It occurs when sunlight is refracted, internally reflected, and dispersed by raindrops, splitting the light into its seven constituent colors. The observer must have the Sun behind them and rain in front to see the rainbow clearly.


Q: Which among the following is the major cause of acid rain ?

A: Carbon dioxide

B: Carbon monoxide

C: Oxygen

D: Nitrogen dioxide



Correct Option: D  [ Nitrogen dioxide ]

Remark:

Nitrogen dioxide (NO₂) is a major cause of acid rain. When released into the atmosphere from vehicle exhausts and industrial emissions, it reacts with water vapor to form nitric acid (HNO₃). Along with sulfur dioxide forming sulfuric acid, it contributes to acid rain, which damages vegetation, aquatic life, and buildings.

  • Carbon dioxide: Causes global warming, not acid rain.
  • Carbon monoxide: A toxic gas but not acidic.
  • Oxygen: Essential for respiration, not a pollutant.


Q: Which one of the following has the highest fuel value ?

A: Hydrogen

B: Charcoal

C: Natural gas

D: Gasoline



Correct Option: A  [ Hydrogen ]

Remark:
"Hydrogen" has the highest calorific value among commonly used fuels because it has a very high energy content, undergoes complete combustion, has a high heat of combustion, and can be used in various applications.
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