Day-644 | Daily MCQs | UPSC Prelims | SCIENCE AND TECHNOLOGY

Answer: B
Explanation
The Specific Absorption Rate (SAR) value is a measure used to quantify the rate at which energy from electromagnetic fields is absorbed by the human body when exposed to radio frequency electromagnetic fields. It represents the amount of radio frequency energy absorbed by a unit mass of tissue, typically expressed in watts per kilogram (W/kg). SAR values are important for assessing the potential health risks associated with exposure to electromagnetic radiation emitted by electronic devices such as mobile phones, Wi-Fi routers, and microwave ovens. Higher SAR values indicate higher levels of radiation absorption, which may increase the risk of adverse health effects such as tissue heating and other biological responses. Regulatory agencies often set SAR limits to ensure that exposure to electromagnetic fields remains within safe levels for human health.
Smartphone makers usually mention the SAR level on the manual box. As per the rules, the SAR level of any device should not exceed 1.6 W per Kg.
You can also check the SAR level by dialing a number. The number is *#07#. When you dial the number, the phone will automatically show the SAR level. If it is more than 1.6 W/Kg, it will harm you.
Telecom Enforcement Resource & Monitoring (TERM) Cells have been entrusted with the job of conducting audits on the self certification furnished by the Service Providers.

Answer: C
Explanation
A catalytic converter is an emissions control device. The job of the catalytic converter is to convert harmful pollutants into less harmful emissions before they ever leave the car’s­ exhaust system.
• Statement 1 is correct: Catalytic converters are designed to reduce toxic emissions such as carbon monoxide (CO), Nitrogen Oxides (Nox), and volatile organic compounds (VOCs) into benign emissions like Nitrogen gas, carbon dioxide, water vapour etc.

• Statement 2 is incorrect: It is the reduction catalyst which changes NOx into nitrogen gas. Reduction catalysts oxidize themselves and reduce others. This way the nitrogen-oxygen bond is broken to change the gas.
• Oxidation catalyst on the other hand oxidises carbon monoxide (CO) into carbon dioxide (CO2) which is less toxic.

Answer: A
Explanation
• Statement 1 is correct: Antimatter particles are almost identical to their matter counterparts except that they carry the opposite charge and spin. Antimatter occurs in natural processes like cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these have successfully been bound together in experiments to form antiatoms.
• Statement 2 is incorrect: When matter and antimatter collide, the particles destroy each other, with a huge energy release. Depending on the colliding particles, not only is there a great energy release, but new, different particles may also be produced (such as neutrinos and various quarks). Dark matter is an altogether another cosmic concept which does not interact with electromagnetic waves.

Answer: B
Explanation
Statement 1 is incorrect: It is carbon nanotube (CNT) which is produced through the CVD technique. In this technique, carbon-bearing gases deposit carbon atoms on a growing nanotube. Carbon fibers, on the other hand, are made up of interlocking sheets of graphene, which in turn are made up of carbon atoms.

Statement 2 is correct: Carbon fibers exist at the microscale of 10^-6 meters whereas CNT are at nanoscale (10^-9 meters). Thus, carbon fibers are about thousand times larger than CNT.

Statement 3 is correct: Like nanotubes, the fibers have a notably high tensile strength and are very stiff. Thus, both of them are ideally used to create composite materials to improve the tensile performances of products.

Answer: A
Explanation
• Statement 1 is correct: This is a very low carb, moderate protein and high fat diet. It typically contains 70% fat, 20% protein, and only 10% carbs. A ketogenic diet is an effective way to lose weight and lower risk factors for various lifestyle diseases.
• Statement 2 is incorrect: Ketosis is a metabolic state in which our body uses fat for fuel instead of carbs. Blood, urine, and breath tests are available, which can help determine whether one has entered ketosis by measuring the amount of ketones produced by the body. Moreover, as the diet is low in carb, so all the glycogen (stored glucose) must be already consumed before the body enters into ketosis.