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Question 461

Decibel is the unit used for

Aintensity of light

Bintensity heat

Cintensity of sound

Dfrequency of radio wave

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C. intensity of soundExplanation: The decibel (dB) is a unit used to measure the intensity or loudness of sound. It expresses sound level on a logarithmic scale relative to a standard reference intensity of 10-12 watt/m², which is the faintest sound the average human ear can hear. Normal conversation is around 60 dB, city traffic about 80–90 dB, and sounds above 120 dB can cause pain or hearing damage. The decibel scale helps compare very large variations in sound intensity conveniently.

Question 460

Light year is a unit of measurement of

Aspeed of light

Bstellar distances

Cspeed of rockets

Dtime

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B. stellar distancesExplanation: A light year is a unit used to measure stellar or astronomical distances. It is defined as the distance that light travels in one year in a vacuum. Since light moves at a speed of about 3 × 108 m/s, one light year equals approximately 9.46 × 1012 km. It is commonly used to express distances between stars and galaxies because these distances are too large to be measured in kilometers or miles.

Question 459

Malaria is caused by

Aparasitic infection

Bviral infection

Cbacterial infection

Dfungal infection

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A. parasitic infectionExplanation: Malaria is caused by a parasitic infection of the genus Plasmodium. The disease spreads to humans through the bite of an infected female Anopheles mosquito. When the mosquito bites, it injects Plasmodium sporozoites into the bloodstream, which travel to the liver, multiply, and infect red blood cells. Common species causing malaria include P. vivax, P. falciparum, P. malariae, and P. ovale. Symptoms include fever, chills, sweating, and anemia. It can be prevented by mosquito control and use of antimalarial drugs.

Question 455

Full form of "GPS" is

AGeographic Pointing System

BGlobal Positioning System

CGeographic Photo Sensor

DGlobal Polar Synchronization

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B. Global Positioning SystemExplanation: The full form of GPS is Global Positioning System. It is a satellite-based navigation system that provides accurate information about the location, speed, and time anywhere on Earth. Developed by the U.S. Department of Defense, GPS uses a network of at least 24 satellites orbiting the Earth. It is widely used in navigation, mapping, military operations, aviation, and smartphone tracking applications.

Question 439

Acid rain is caused by

AHumidity

BPollutant gases

CPopulation explosion

DNone of these

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B. Pollutant gasesExplanation: Acid rain is caused by the presence of pollutant gases such as sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) in the atmosphere. These gases are released mainly from burning of coal, oil, and industrial emissions. When they combine with water vapor in the atmosphere, they form sulphuric acid (H₂SO₄) and nitric acid (HNO₃), which fall to the ground as acid rain. It damages soil, plants, aquatic life, and even buildings and monuments made of marble or limestone.

Question 438

The virus infection causes AIDS is known as

AHIV

BHID

CDIV

DNone of theses

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A. HIVExplanation: The disease AIDS (Acquired Immuno Deficiency Syndrome) is caused by the HIV (Human Immunodeficiency Virus). HIV attacks the body’s immune system, specifically the CD4 or T-helper cells, weakening the body’s ability to fight infections and diseases. It spreads through unprotected sexual contact, sharing of infected needles, transfusion of contaminated blood, or from an infected mother to her child during birth or breastfeeding. There is no permanent cure, but antiretroviral therapy (ART) helps control the virus and prolong life.

Question 437

Which is an example of pollution-free energy?

ACoal

BWind energy

CMineral oil

DNone of these

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B. Wind energyExplanation: Wind energy is a clean and renewable source of energy that does not cause environmental pollution. It is generated by converting the kinetic energy of moving air into mechanical or electrical energy using wind turbines. Unlike fossil fuels such as coal or mineral oil, wind energy does not release carbon dioxide, sulfur dioxide, or other greenhouse gases. It is, therefore, a pollution-free and sustainable source of power, widely used for electricity generation in wind farms.

Question 436

The sex of a child before birth can be determined by:

AAmnoscopy

BAmniocentesis

CAmniograpghy

DNone of these

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B. AmniocentesisExplanation: Amniocentesis is a medical diagnostic procedure used to determine the genetic and chromosomal makeup of a developing fetus. It involves the withdrawal of a small amount of amniotic fluid from the uterus using a fine needle. This fluid contains fetal cells that can be tested to identify genetic disorders such as Down’s syndrome and also to determine the sex of the fetus. However, using amniocentesis for sex determination is illegal in India under the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act to prevent female foeticide.

Question 435

The function of Kidney is to:

APurify blood

BFight against infection

CDigest the food

DNone of these

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A. Purify bloodExplanation: The main function of the kidneys is to purify blood by removing waste products, excess salts, and extra water from the body in the form of urine. Each kidney contains about one million nephrons, which are the structural and functional units responsible for blood filtration. The kidneys also help in maintaining the acid-base balance, water balance, and blood pressure, and play a role in hormone secretion such as erythropoietin (for RBC production).

Question 434

How much blood does a man have in his body?

A4 %

B10 %

C7 %

DNone of these

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C. 7 %Explanation: In a healthy adult, the total volume of blood in the body is approximately 7% of body weight. For an average person weighing around 70 kg, this equals about 5 to 5.5 litres of blood. Blood plays a vital role in transporting oxygen, nutrients, hormones, and waste products throughout the body. It also helps regulate temperature and maintain pH balance. The major components of blood are plasma (55%), red blood cells (RBCs), white blood cells (WBCs), and platelets.

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Science

Decibel is the unit used for

Light year is a unit of measurement of

Malaria is caused by

Full form of "GPS" is

Acid rain is caused by

The virus infection causes AIDS is known as

Which is an example of pollution-free energy?

The sex of a child before birth can be determined by:

The function of Kidney is to:

How much blood does a man have in his body?

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