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The correct option is the brain.

EXPLANATION:

• The Pituitary gland is also known as the hypophysis.
• The pituitary gland is a pea-sized endocrine gland situated at the base of our brain.
• The pituitary gland releases growth hormones.

Additional Information

• It is often referred to as the ‘Master Gland’ because it produces some of the important hormones in the body.
• It is situated in a bony structure called the Pituitary fossa, just below the hypothalamus, close to the optic nerve.
• The pituitary gland is divided into three parts, also called lobes:
• Anterior pituitary
• Intermediate pituitary (Absent in adult human beings)
• Posterior pituitary
• Function Of Hormones Secreted By Pituitary Gland
• A healthy adult human’s pituitary gland consists of two parts – the Anterior and the Posterior parts.
• The Intermediate pituitary regresses during gestation and is absent in adult humans.
• Anterior Pituitary Hormones
• The anterior pituitary is responsible for the synthesis and secretion of several key hormones in the body. These hormones include:
• Human Growth Hormone (HGH): Responsible for the growth and repair of all cells in the body.
• Thyroid Stimulating Hormone (TSH): Influences the thyroid gland for the release of thyroxine, its own hormone. TSH is also called Thyrotropin.
• Posterior Pituitary Hormones
• The posterior pituitary is responsible for the storage and secretion of two very important hormones:
• Antidiuretic Hormone (ADH): Controls the water balance of the body by affecting the reabsorption of water by the kidneys
• Oxytocin: Controls certain aspects of pregnancy and childbirth such as uterine contraction and production of milk.

The correct option is Ultrasonic waves.

EXPLANATION:

Ultrasonic waves:

• Ultrasonography is the technique used for producing images of internal organs and tissues.
• The ultrasound scanner is a device that uses ultrasonic waves for capturing the images of internal organs and tissues.
• Ultrasonic waves travel through the body and get reflected back where there is a change in tissue density.
• These waves are then converted into electrical signals, which in turn are used to generate images of the organs.
• It is used to know the growth of the fetus in the womb during pregnancy and to check for any abnormalities.
• It is also used to break stones formed in the kidneys.

The correct answer is AB.

CONCEPT:

The ABO Blood grouping System

• The ABO blood group system is the most important blood type system (or blood group system) in human blood transfusion.

​The ABO

• Based on the presence or absence of antigen A and antigen B, blood is divided into four groups
• ‘A, B, AB, and ‘O’ group. ​
• Blood having antigen A belongs to the ‘A’ group.
• This blood has β-antibody in the serum.
• ​Blood with antigen B and α-antibody belongs to the ‘B’ group.
• If both the antigens are present, the blood group is called the ‘AB’ group, and the serum of this group does not contain any antibodies.
• If both antigens are absent, the blood group is called the ‘O’ group, and both α and β antibodies are present in the serum.
• Principle of Blood Grouping o Blood grouping is done on the basis of agglutination.​

Blood Groups and Donor Compatibility

EXPLANATION:

AB+ is known as the 'universal acceptor' because it has both antigens and no antibodies and also has the Rh factor.

The correct option is lungs.

EXPLANATION:

• Pneumonia is an acute respiratory infection of the lungs.
• It is also a Pneumococcal disease caused by bacteria called Streptococcus pneumoniae or pneumococcus.
• it can develop from either bacteria, viruses or fungi in the air.
• Children whose immune systems are immature (i.e. newborns) or weakened – such as by undernourishment, or diseases like HIV – are more vulnerable to pneumonia.
• Pneumonia is contagious and can be spread through coughing or sneezing.
• It can also be spread through fluids, like blood during childbirth, or from contaminated surfaces.

The correct option is concave.

Concept:

A mirror is a smooth surface on which regular reflection takes place.

A clear image of an object placed in front of a mirror is formed due to the reflection of light.

A mirror can be plane or spherical (concave and convex).

Characteristics of the image formed by plane mirror:

• The image formed is virtual and erect.
• It is of the same size as that of the object.
• It is formed as far behind the mirror as the object is in front of it.
• The image formed shows lateral inversion i.e., left-right reversal of the object.

Characteristics of the image formed by Convex mirror or concave lens:

• Both convex mirror and concave lens always form a diminished, erect and virtual image.

Characteristics of the image formed by the Concave mirror:

• The image formed can vary from being highly magnified, magnified, the same size, diminished, or highly diminished.
• It can be either real and inverted or virtual and erect.

EXPLANATION:

 From the above, it is clear that only a concave mirror can be formed an enlarged image.

The correct option is our perspiration evaporates rapidly.

CONCEPT:

Demonstrates the heat transfer mechanism in the human body:

Perspiration is basically sweating which occurs in the human body because of the sweat glands present under the skin.

Radiation is only dependent on the absolute Temperature it has nothing to do with air or without air, the intensity of radiation remains the same.

A fan in a room circulates the air which is present inside the room, it never provides cooler or warmer air rather it provides the air at the room temperature.

The conductivity of air is a function of temperature so a sole fan can never change the temperature of the air as we know fan only circulates the air at the room temperature thus conductive doesn’t change by the virtue of the fan.

The process by which the human body gives off heat (Tambient < Tskin):

The process by which the human body receives heat (Tambient > Tskin):

When the ambient temperature is above body temperature, then radiation, conduction, and convection all transfer heat into the body rather than out. Since there must be a net outward heat transfer, the only mechanisms left under those conditions are the evaporation of perspiration from the skin and the evaporative cooling from exhaled moisture.

If part of a liquid evaporates, it cools the liquid remaining behind because it must extract the necessary heat of vaporization from that liquid in order to make the phase change to the gaseous state. It is, therefore, an important means of heat transfer in certain circumstances, such as the cooling of the human body when it is subjected to ambient temperatures above the normal body temperature.

EXPLANATION:

• A fan produces a feeling of comfort during hot weather because our perspiration evaporates rapidly.
• Perspiration is basically sweating which occurs in the human body because of the sweat glands present under the skin.
• Due to the warm weather condition, we sweat. Now as the sweat comes out it spreads over the skin, this sweat evaporates under the action of the fan blowing the air which results in effective convection thus taking away the heat from the skin resulting in the cooling effect.

The correct option is the refraction of light.

CONCEPT:

• Refraction: The phenomenon by which a ray of light bends its path when it travels from one transparent medium to another is called refraction of light.
• The bending happens because the speed of light varies in different mediums.
• Refractive index: The ratio of the speed of light in the air to the speed of light in the medium is called the refractive index. More will be the ratio of refractive index between two mediums more will be the bending of light.
• Atmospheric Refraction: The different layers of the atmosphere have a different refractive indexes. The ray of light coming from some outer space changes continuously bends its path while passing through different atmospheric layers.

EXPLANATION:

• The atmosphere of the earth is made of different layers.
• It is affected by winds, varying temperatures, and different densities as well.
• When light from a distant source (a star) passes through our turbulent (moving air) atmosphere, it undergoes refraction many times.
• When we finally perceive this light from a star, it appears to be twinkling.
• This is because some of the light rays reach us directly and some bend away from and toward us. It happens so fast that it gives a **twinkling effect.**​

Important Points

• This twinkling effect does not happen to the sun or moon because they are very close to the earth and appear big.
• Stars are very far and appear to us as point size. So, the twinkling effect is visible.

The correct answer is an uncontrolled fusion reaction.

CONCEPT:

• Hydrogen Bomb
• It contains a mixture of deuterium oxide and tritium oxide in a space surrounding an ordinary atom bomb.
• The first step of the reaction is endothermic i.e. reaction between deuterium oxide and tritium oxide is initiated by the energy obtained from the explosion of the atom bomb.
• The second step of the reaction is exothermic i.e. energy evolving.
• Nuclear Fusion
• The process which involves the fusion of two or lighter nuclei to give heavier nuclei is called nuclear fusion.
• It occurs only at extremely high temperatures (>106K), so also called thermonuclear reactions.
• It is used in a hydrogen bomb.
• The energy of the sun and stars is also a result of a series of nuclear fusion reactions.

EXPLANATION:

• The hydrogen bomb is also known as the Thermonuclear bomb or H-bomb.
• A hydrogen bomb is a weapon whose enormous explosive power results from an uncontrolled self-sustaining chain reaction in which isotopes of hydrogen combine under extremely high temperatures to form helium in a process known as nuclear fusion.
• So from above, it is clear that the hydrogen bomb is based on the principle of uncontrolled fusion reaction.

Additional Information

• Nuclear Fission
• It is the phenomenon of artificial transmutation in which a heavy nucleus splits up into two or more lighter nuclei of nearly comparable mass with the release of a tremendous amount of energy.
• It was discovered by two German scientists Otto Hahn and Fritz Strassmann in 1939.

The correct option is for water starts boiling at a high temperature due to high pressure.

EXPLANATION:

• Food is cooked faster in a pressure cooker because due to high pressure the boiling point of water is raised.
• A pressure cooker works on the principle that with rising pressure the boiling point of water increases.
• Due to the high-pressure boiling point of water rising from 100o C to around 120o C.
• So, the steam also becomes hotter and is also trapped inside the cooker resulting in faster cooking of food.
• When cooked in open vessels the hot air escapes.
• But in the pressure cooker moisture surrounding the food itself reaches higher temperatures than it would without the pressure which speeds the cooking.
• So, the cooking speed is increased nearly four times.

CONCEPT:

Refrigerator or Heat Pump:

• A refrigerator or heat pump is basically a heat engine run in the reverse direction.
• It essentially consists of three parts

1. Source (Atmosphere)):  At higher temperature T1.
2. Working substance: It is called refrigerant liquid ammonia and freon works as a working substance.
3. Sink (Contents of a refrigerator): At lower temperature T2.

EXPLANATION:

• As we know the Refrigerator transfers heat from a cold to a hot body at the expense of mechanical energy supplied to it by an external agent.
• If a refrigerator’s door is kept open, then the room will become hot, because of then refrigerator exhaust more heat into the room than earlier.
• In this way, the temperature of the room increases and the room becomes hot. Therefore option 1 is correct.
• As we know that no refrigerator is efficient according to the second law of thermodynamics.
• Thus it exhausts more heat into the room than it extracts from it. Thus, a room cannot be cooled by keeping the door of a refrigerator open.