Question Discussion & Solution

The correct answer is to Correct the eye defects.

• Lenses are widely used in spectacle to correct eye defects.
• There are three common defects of vision that can be corrected with the help of suitable spherical lenses (convex lenses or concave lenses).
• Myopia is also known as Short-sightedness or nearsightedness.
  • Due to this defect, the person cannot see the distant objects clearly but he/she can see the nearby objects clearly.
  • The far point of the eye having myopia is less than infinity.
  • The defect is caused due to the high converging power of eye-lens or due to the eyeball being too long.
  • It can be corrected by making use of spectacles containing concave lenses.
• Hypermetropia is also known as Long-sightedness or farsightedness.
  • Due to this defect, the person cannot see the nearby objects clearly but he/she can see the distant objects clearly.
  • The near point of a hypermetropic eye is more than 25 centimetres away.
  • The defect is caused due to the low converging power of eye-lens or due to the eye-ball being too short.
  • It can be corrected by making use of spectacles containing convex lenses.
• Presbyopia is a vision disease caused mostly in old age.
  • The ciliary muscles become weak and the eye-lens become rigid and the eye loses its power of accommodation in old age in this vision defect.
  • In Presbyopia the person cannot see the nearby objects clearly due to loss of power of accommodation of the eye.
  • The near point of the old person having presbyopia gradually reduces and becomes much more than 25 centimetres away.
  • It can be corrected by making use of spectacles containing convex lenses.
• A person suffering from both Myopia and Hypermetropia uses spectacles having bifocal lenses in which the upper part consists of a concave lens to correct myopia and the lower part consists of a convex lens to correct hypermetropia.

The correct answer is Ethyl mercaptan.

Key Points

• The stench due to leakage from the LPG cylinder because of Ethyl mercaptan.
  • LPG gas is basically propane and butane.
  • It is odourless in its natural state.
  • The smell that you notice when there is a leak is actually the stench of an entirely different agent, called ethyl mercaptan​.
    • This substance is added to the gas when it leaves the main storage terminals.
• Hence, option 4 is correct.

Additional Information

• Methane :
  • Methane is a chemical compound with the chemical formula CH₄.
  • Methane is a one-carbon compound in which the carbon is attached by single bonds to four hydrogen atoms
  • It is a group-14 hydride and the simplest alkane and is the main constituent of natural gas.
  • It is a colourless, odourless, non-toxic but flammable gas.
  • It has a role as a fossil fuel, a member of greenhouse gas, and a bacterial metabolite.
• Butane :
  • Butane or n-butane is an alkane with the formula C₄H₁₀.
  • Butane is a gas at room temperature and atmospheric pressure.
  • Butane is a highly flammable, colourless, easily liquefied gas that quickly vaporizes at room temperature.
  • Butane is a hydrocarbon and a highly flammable, colourless, odourless, easily liquefied gas.
  • It is typically used as fuel for cigarette lighters and portable stoves, a propellant in aerosols, a heating fuel, a refrigerant.
• Propane :
  • Propane is a three-carbon alkane with the molecular formula C₃H₈.
  • It is a gas at standard temperature and pressure, but compressible to a transportable liquid. 
  • Propane is a flammable hydrocarbon gas that is liquefied through pressurization and commonly used for fuel in heating, cooling, hot water, and vehicles.
  • Propane can also be used for refrigerants, aerosol propellants, and petrochemical feedstock.​ 

The correct answer is Digital Camera.

Key Points

• An input device is any hardware device that sends data to a computer, allowing us to interact with and control it.
• For instance- Keyboard, Mouse, Joy Stick, Light pen, Track Ball, Scanner, Graphic Tablet, Microphone.
• A digital camera is an input device that captures images (and sometimes video) digitally.
• Digital cameras use an image sensor chip to capture the image.
• However, it can also be used as an output device. The digital camera can send pictures to our computer.
• An output device is any hardware device used to send data from a computer to another device or user.
• Examples of output devices are-
  • monitors and projectors (video), headphones and speakers (audio), or printers and plotters (physical reproduction in the form of text or graphics).

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

The correct answer is Waist.

• Kandora ornament is worn on Waist.
• Kandora is similar to Kardhani but its design is different.

Additional Information