Tag: science & technology

The Sun loses approximately 1.3 to 1.9 million tons (1.3-1.9 billion kilograms) of mass every second due to solar wind and nuclear fusion converting mass to energy. This continuous mass loss is a fundamental process in stellar evolution.

Herpetology is the branch of zoology concerned with the study of amphibians and reptiles. The other options refer to different fields: Ornithology (birds), Oncology (cancer treatment), and Oology (study of eggs). Note the spelling should be 'Herpetology' with two 'e's.

Manganese is a trace element present in very small quantities in the human body (10-20 mg), unlike sodium and potassium which are macrominerals present in much larger amounts (100-140 g). Aluminium is not considered essential for human life. Trace elements like manganese are required in minute quantities for proper enzyme function.

Minamata disease is a neurological syndrome caused by severe mercury poisoning. It was first discovered in Minamata City, Japan in 1956, caused by industrial methylmercury pollution in Minamata Bay. Mercury is a heavy metal that accumulates in fish and shellfish, causing serious health issues when consumed by humans.

Caffeine is a natural stimulant present in cola drinks and other caffeinated beverages. It's extracted from coffee beans, tea leaves, or kola nuts. Cola drinks typically contain 30-50 mg of caffeine per serving. Nicotine is from tobacco, methanol is toxic alcohol, and benzonate is a preservative, not naturally present in cola.

Cobalt is an essential component of Vitamin B12 (cobalamin), which is required for red blood cell formation and neurological function. Absence of cobalt (and thus Vitamin B12) leads to pernicious anemia, a condition where the body cannot produce enough healthy red blood cells. This causes fatigue, weakness, and neurological problems. The other options are not related to cobalt deficiency.

In acidic soils (low pH), aluminium becomes soluble and toxic to plant roots, inhibiting root growth and nutrient uptake. This is a major problem in agriculture on acidic tropical soils. Other options like carbon, zinc, and iron are either not typically toxic in these conditions or essential micronutrients. Aluminium toxicity is a well-documented issue in soil science.

Hydrogen has the highest calorific value (~150 MJ/kg) among common fuels, meaning it releases the most energy per gram during combustion. Carbon produces significantly less heat (~33 MJ/kg), while helium is a noble gas that does not burn, and silicon is not used as a fuel.

Nitrogen dioxide (NO2) is used as an antichlor in bleaching and textile processes because it acts as a reducing agent to neutralize excess chlorine. Hydrogen sulfide and sulfur dioxide are also reducing agents but are not typically called antichlors. Ammonium nitrate is an oxidizer, not an antichlor.

Carbon-14, a radioactive isotope of carbon, is used in radiocarbon dating to determine the age of organic materials up to about 50,000 years old. The amount of Carbon-14 remaining in a sample indicates how long it has been since the organism died. Hydrogen, gold (Aurum), and sulfur do not have suitable radioactive isotopes for dating.