Question Discussion & Solution

The correct answer is Cancer.

Concept: 

Infectious diseases:

• Infectious disease are diseases caused by bacteria, fungi, viruses, or parasites.
• Infectious diseases are transmitted by infectious agents.
• Infectious disease is spread by humans, plants, and insects. 
• Agents that spread pathogens or pass them on are known as vectors or disease intermediaries.

Explanation:

• Cancer is not an infectious disease. 
• Cancer cannot be passed from one person to another by breathing the same air, sharing a toothbrush, touching.
• Cancer is a disorder in which cell growth is uncontrolled.
• Changes in genes that control how our cells function, particularly how they grow and divide, cause cancer.
• Accelerating cell division rates or inhibiting normal control can result in gene mutations. 
• Cancer is sometimes caused by the genes we inherit from our parents.
• Cancer's Causes
  • Carcinogens such as tobacco, chemicals, alcohol, and ultraviolet radiation from the sun are among the leading causes of cancer.

Additional Information

• Cholera:
  • Cholera is a severe diarrheal infectious disease caused by Vibrio cholerae bacteria.
  • People who consume cholera-contaminated food or water may become ill.
  • The infection is frequently mild or without symptoms, but it can also be severe and life-threatening.
  • The disease's deadly effects are caused by a toxin produced by bacteria in the small intestine.
• TB (Tuberculosis):
  • Tuberculosis (TB) is an infectious disease caused by a Mycobacterium tuberculosis bacteria.
  • It was transmitted from person to person via microscopic droplets released into the air.
  • Usually bacteria attack the lungs, but tuberculosis bacteria can attack any part of the body, including the brain, kidney, and spine.
• Conjunctivitis: 
  • Conjunctivitis or pink eye is a viral disease that is caused by allergies or bacterial or viral infection.
  • It is the Inflammation or infection of the eyeball's outer membrane and the inner eyelid.
  • Conjunctivitis is highly contagious and is spread through contact with infected people's eye secretions

CONCEPT:

Equilibrium of a rigid body:

• A rigid body is said to be in mechanical equilibrium if both its linear momentum and angular momentum are not changing with time, or equivalently, the body has neither linear acceleration nor angular acceleration.
• Condition for the mechanical equilibrium:
  1. The total force, i.e. the vector sum of the forces, on the rigid body is zero.
  2. The total torque, i.e. the vector sum of the torques on the rigid body is zero.

⇒ \(\rm\vec{F_1}+\vec{F_2}+...+\vec{F_n}=0\)

⇒ \(\rm \vec{τ_1}+\vec{τ_2}+...+\vec{τ_n}=0\)

• If the forces on a rigid body are acting in the 3 dimensions, then six independent conditions to be satisfied for the mechanical equilibrium of a rigid body.
• If all the forces acting on the body are coplanar, then we need only three conditions to be satisfied for mechanical equilibrium.
• A body may be in partial equilibrium, i.e., it may be in translational equilibrium and not in rotational equilibrium, or it may be in rotational equilibrium and not in translational equilibrium.

EXPLANATION:

• A rigid body is said to be in mechanical equilibrium if both its linear momentum and angular momentum are not changing with time, or equivalently, the body has neither linear acceleration nor angular acceleration.
• We know that the linear acceleration and the angular acceleration of a stationary body are zero.

A book is kept on a table:

• In this case, the book will be stationary so it is an example of the equilibrium of a body.

A ball is moving downward freely under gravity:

• We know that when a ball moves freely under gravity, then only the gravitational force will act on the ball due to which the ball accelerates downward.
• Therefore ball is moving downward freely under gravity is not an example of the equilibrium of a body.
• Hence, option 1 is correct.

The correct answer is Microphone.

• ​A microphone is an input device, which is used to save a person's voice on a computer.

Key Points

• Microphone
  • The microphone is a device connected to a computer (via an audio interface or another analog-to-digital converter).
  • It sends/inputs information into the computer.
  • This means microphones are input devices.

​Additional Information

• Speaker
  • Speakers are one of the most common output devices.
  • The purpose of speakers is to produce audio output that can be heard by the listener.
• Scanner
  • ​A scanner is an input device that scans documents such as photographs and pages of text.
  • When a document is scanned, it is converted into a digital format. 
• Joystick
  • ​A joystick is an input device.
  • It can be used for controlling the movement of the cursor or a pointer in a computer device.

Bleaching powder:

• Calcium hypochlorite is known as bleaching powder.​
• It is a pale yellowish powder having a strong smell of chlorine.
• It is soluble in cold water.
• Bleaching powder reacts with dilute acids to produce chlorine.
• When bleaching powder is treated with an excess of a dilute, all the chlorine present in it is liberated.
• It is used in bleaching clothes in the laundry due to its oxidizing property.

Formula- CaOCl₂ 

Additional Information

• Washing powder: The chemical name of washing soda is Sodium carbonate Decahydrate and the chemical formulae is Na_2​CO3​.10H_2​O.
• Baking powder: Sodium hydrogen carbonate is the chemical term for the baking powder with chemical formulae NaHCO₃.
• Soda ash: Anhydrous Sodium carbonate is known as Soda ash with chemical formulae Na₂CO₃.

The correct answer is All of these

• An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.
• The three most common operating systems for personal computers are Microsoft Windows, Mac OS X, and Linux.
• Modern operating systems use a graphical user interface(GUI).
• An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is a software that performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.
• Some popular Operating Systems include Linux Operating System, Windows Operating System, VMS, OS/400, AIX, z/OS, etc.
• The following are some of the important functions of an operating system:
  • Memory Management
  • Processor Management
  • Device Management
  • File Management
  • Security
  • Control over system performance
  • Job accounting
  • Error detecting aids
  • Coordination between other software and users