Q1. With reference to street-lighting, how do sodium lamps differ from LED lamps?
- Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
- As street-lights, sodium lamps have a longer lifespan than LED lamps.
- The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting.
How many of the statements given above is/are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Ans: (b)
Explanation:
- The correct answer is (b), 1 and 3 only.
- Sodium lamps do produce light in 360 degrees, while LED lamps emit light in a more directional beam. This means that LED lamps can be used to create more targeted lighting, which can reduce light pollution and save energy.
- LED lamps also have a longer lifespan than sodium lamps, and they offer a wider range of color temperature options. This can be beneficial for street lighting, as it can improve visibility and safety.
- However, sodium lamps are less expensive to purchase than LED lamps. In addition, sodium lamps have been used for street lighting for many years, so there is a lot of experience with their installation and maintenance.
- Overall, LED lamps offer a number of advantages over sodium lamps for street lighting. However, the higher initial cost of LED lamps may be a barrier for some communities.
Q2. The term ‘ACE2’ is talked about in the context of:
(a) genes introduced in the genetically modified plants
(b) development of India’s own satellite navigation system
(c) radio collars for wildlife tracking
(d) spread of viral diseases
Ans: (d)
Explanation:
- The term “ACE2” is talked about in the context of the spread of viral diseases. So the answer is (d).
- ACE2 is a protein that acts as a receptor for some coronaviruses, including SARS-CoV-2, the virus that causes COVID-19. When the virus binds to ACE2, it can enter the cell and replicate.
- ACE2 is expressed in a variety of cells throughout the body, including those in the lungs, heart, kidneys, and intestines. This is why SARS-CoV-2 can cause a variety of symptoms, including respiratory problems, heart problems, kidney problems, and gastrointestinal problems.
- Scientists are still learning about the role of ACE2 in the spread of viral diseases. However, it is clear that ACE2 is an important target for antiviral drugs and vaccines.
Q3. Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
(a) Low-density polyethylene
(b) Polycarbonate
(c) Polyethylene terephthalate
(d) Polyvinyl chloride
Ans: (b)
Explanation:
- Bisphenol A (BPA) is a structural component in the manufacture of polycarbonate plastics. So the answer is (b).
Polycarbonate plastics are used in a variety of products, including:
- Water bottles
- Food containers
- Baby bottles
- Medical devices
- Eyeglasses
- Safety glasses
- CDs and DVDs
- Automotive parts
- Electrical components
- BPA can leach into food and beverages from polycarbonate containers, especially when the containers are heated or damaged. BPA exposure has been linked to a number of health concerns, including reproductive problems, developmental delays, and increased risk of some types of cancer.
- For this reason, some countries have banned or restricted the use of BPA in certain products, such as baby bottles. However, BPA is still widely used in polycarbonate plastics.
Q4. ‘Triclosan’, considered harmful when exposed to high levels for a long time, is most likely present in which of the following?
(a) Food preservatives
(b) Fruit-ripening substances
(c) Reused plastic containers
(d) Toiletries
Ans: (d)
Explanation:
- Triclosan is a broad-spectrum antimicrobial agent that is used in a variety of products, including toiletries. So the answer is (d).
Triclosan is most commonly found in personal care products, such as:
- Soap
- Hand sanitizer
- Toothpaste
- Mouthwash
- Deodorant
- Body wash
- Cosmetics
- It is also used in some household cleaning products, such as dish soap and laundry detergent.
- Triclosan is effective at killing bacteria and preventing the growth of mold and mildew.
However, there are concerns that triclosan exposure may have harmful health effects, such as:
- Hormonal disruption
- Antibiotic resistance
- Skin irritation
- Allergies
- In 2016, the US Food and Drug Administration (FDA) banned the use of triclosan in antibacterial soap, citing concerns about safety and efficacy. However, triclosan is still allowed in other personal care products and household cleaning products.
Q5. Which one of the following is a reason why astronomical distances are measured in light-years?
(a) Distances among stellar bodies do not change.
(b) Gravity of stellar bodies does not change.
(c) Light always travels in a straight line.
(d) Speed of light is always the same.
Ans: (d)
Explanation:
- The correct answer is (d), Speed of light is always the same.
- The speed of light is a constant value of approximately 300,000 kilometers per second (186,000 miles per second). This means that light travels the same distance in the same amount of time, regardless of the observer’s motion or the position of the light source.
- Astronomical distances are so vast that it is impractical to measure them in kilometers or miles. For example, the nearest star to our sun, Proxima Centauri, is about 4.2 light-years away. This means that the light from Proxima Centauri takes 4.2 years to reach Earth.
- Measuring astronomical distances in light-years makes it easier to comprehend the scale of the universe. It also allows astronomers to determine how far back in time they are looking. For example, when we look at Proxima Centauri, we are actually seeing it as it was 4.2 years ago. This is because the light from Proxima Centauri has taken 4.2 years to reach us.
