Science & Technology Fundamentals Quiz

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.

Fluorine (as fluoride compounds) is added to toothpaste to help prevent tooth decay and strengthen enamel. Silicon, potassium, and aluminum are not used in toothpaste for dental health. The capitalized spellings in options are typos but the intended answer is clear.

The choke (ballast) in a tube light circuit provides a momentary high voltage surge to initiate the ionization process in the tube, which then allows current to flow. This voltage spike is necessary because the mains voltage is insufficient to start the discharge. The choke does NOT decrease current or voltage - it actually causes a voltage spike.

Yahoo was founded in January 1994 by Jerry Yang and David Filo, who were graduate students at Stanford University at the time. They originally named it 'Jerry and David's Guide to the World Wide Web' before renaming it to Yahoo. Dennis Ritchie and Ken Thompson developed Unix, Vint Cerf and Robert Kahn developed TCP/IP, and Steve Case founded AOL while Jeff Bezos founded Amazon.

A squirrel cage induction motor is an AC motor and cannot function as a DC machine without additional complex conversion equipment. The other options can all work with DC: permanent magnet motors use DC directly, series motors (universal motors) can run on both AC and DC, and synchronous motors can be designed for DC operation.

Sabeer Bhatia co-founded Hotmail with Jack Smith in 1996, and Microsoft acquired it in 1997 for approximately $400 million. Shawn Fanning founded Napster, Ada Lovelace was a pioneering computer programmer, and Ray Tomlinson invented email.

The deflection yoke contains electromagnetic coils that steer the electron beam horizontally and vertically across the CRT screen to create the image. Transformers change voltage, capacitors store electrical charge, and diodes rectify AC to DC.

NTSC (National Television System Committee) was the analog television broadcast standard used in North America and Japan. PAL is used in most of Europe, SECAM in France, and RGB is a color model not a broadcast standard.

Californium is considered the most expensive substance in the world, costing approximately $27 million per gram. It is a radioactive element with very limited production and specialized applications in nuclear reactors and detectors. Cesium, niobium, and anthracene are much more common and less expensive.

Helium is the only element that never solidifies at atmospheric pressure, even at absolute zero. It remains liquid unless pressure above 25 atmospheres is applied. Nitrogen and argon can solidify at low temperatures, and stroncium (misspelled - should be strontium) is a solid metal at room temperature.

Germanium is a semiconductor material, meaning it has electrical conductivity between a conductor and insulator. Germanium and silicon are the two most common elemental semiconductors used in electronic devices. Aluminium is a conductor, while boron and cadmium are not semiconductor materials.

Transistors have three terminals: emitter, collector, and base. A 'receiver' is not a transistor terminal but rather a complete electronic device or component. The question tests knowledge of basic BJT (Bipolar Junction Transistor) structure.

Channel is not a type of diode. Tunnel diode, Schottky diode, and LED (light emitting diode) are all specialized diode types. A 'channel' refers to the conducting path in a MOSFET or field-effect transistor, not a diode category.

In resistor color coding, silver indicates a tolerance of ±10%. Gold represents ±5%, while no color band typically means ±20%. Green is used for the digit 5 in the significant figures, not tolerance. Copper brown is not a standard tolerance band color.

For three identical resistors in parallel, the equivalent resistance is R/n where n is the number of resistors. Here: 30kΩ / 3 = 10kΩ. Series would add them (90kΩ), and the other options (300kΩ, 33kΩ) are not parallel combinations of equal resistors.