science & technology Online Quiz - 263

Rg is roentgenium, named after Wilhelm Roentgen who discovered X-rays. 'Rogernium' is fictional, and Rutherfordium is Rf. Silver is Ag. Roentgenium is a synthetic transition metal in the same group as copper, silver, and gold.

K is the symbol for potassium, derived from its Latin name 'kalium'. This is why potassium uses K instead of Po. 'Kelium' and 'Krypton' (Kr) are incorrect - krypton is a different noble gas. Potassium is an essential alkali metal.

Mercury is the closest planet to the Sun in our solar system, with an average distance of about 58 million kilometers. Venus is the second closest, while Earth is third. Pluto is no longer classified as a major planet.

Pb is the chemical symbol for lead, derived from the Latin word 'plumbum.' Lead is a heavy metal with atomic number 82. Plutonium is Pu, boron is B, and phosphorus is P.

Thomas Edison invented the phonograph in 1877, which was the first device capable of recording and reproducing sound. Alexander Graham Bell is associated with the telephone, Benjamin Franklin with electricity experiments, and Samuel Morse with the telegraph.

Gravity is the force of attraction between any two objects that have mass. It's one of the four fundamental forces of nature. Force is a push or pull, acceleration is rate of velocity change, and work is force times distance.

Giraffes are the tallest living animals, with adults reaching 5.5 to 6 meters in height. Their exceptionally long necks allow them to reach leaves high in acacia trees. Elephants are the largest land animals by mass, but not the tallest.

NaCl is the chemical formula for sodium chloride, commonly known as salt. It's composed of sodium (Na) and chlorine (Cl) ions. Vinegar is acetic acid, pepper is a spice blend, and sugar is sucrose.

Einstein's famous equation is E=mc², where E is energy, m is mass, and c is the velocity of light. The speed of light squared (c²) is the conversion factor between mass and energy.

Mercury is the only metal that is liquid at standard room temperature (20-25°C). It has a melting point of -38.83°C and boiling point of 356.73°C. All other metals are solid at room temperature.

The atomic bomb dropped on Hiroshima on August 6, 1945 was code-named 'Little Boy.' The bomb dropped on Nagasaki on August 9, 1945 was called 'Fat Man.' Little Boy used uranium-235 while Fat Man used plutonium.

Autoclaves sterilize using saturated steam under pressure (typically 121°C, 15 psi for 15-20 minutes). The pressure allows steam to reach temperatures above 100°C without boiling, effectively killing all microorganisms including spores. Dry heat (A) requires higher temperatures (160-170°C) for longer durations.

Photobiology is the study of light's effects on living organisms, primarily focusing on visible and ultraviolet radiation. It encompasses photosynthesis, vision, photomorphogenesis, and light damage. Bioluminescence (D) is one phenomenon studied, but photobiology is broader than just organisms producing light.

Autoclaves sterilize using saturated steam under pressure, typically at 121°C for 15-20 minutes. The pressure prevents water from boiling at 100°C, allowing higher temperatures that kill all microorganisms. This method is more effective than boiling water (C) or dry heat (A).

The magnet test is a common field screening method for identifying stainless steel. Most stainless steel (austenitic grades like 304) is non-magnetic, so a magnet won't stick. However, some stainless steels (ferritic/martensitic grades) are magnetic, so this test isn't definitive but serves as a quick indicator.

A virus is malicious code that attaches itself to legitimate programs and replicates when those programs execute. A worm (A) can replicate independently without attaching to other programs. A Trojan horse (B) appears legitimate but doesn't self-replicate. Terminator (C) is not a malware type.

Pure water has the highest specific heat capacity (4.18 J/g°C) and thermal conductivity among the options, enabling it to absorb heat most rapidly. Salt water has slightly lower specific heat capacity. Motor oil has much lower heat capacity and thermal conductivity, making it the slowest coolant.

In monitor specifications, the format is horizontal_resolution × vertical_resolution × color_depth. So 640×480 is the pixel resolution and 256 represents the number of colors the monitor can display simultaneously (8-bit color, 2^8 = 256). This was common in VGA-era displays.

In the binary system used by computers, 1 kilobyte equals 2^10 bytes, which is 1024 bytes, not 1000 as in the decimal system. This is because computers work in base-2 arithmetic. 256 bytes is 1/4 KB, 512 is 1/2 KB, and 1.44 MB is a floppy disk capacity.

Approximately 71% of Earth's surface is covered by water, with oceans accounting for about 96.5% of all water. This is why Earth appears blue from space and is called the Blue Planet. The other options (25%, 55%, 40%) significantly underestimate the extent of water coverage.