Tag: science & technology

CPU stands for Central Processing Unit. It is the primary component of a computer that executes instructions and processes data. The 'Power' and 'Public' options are incorrect.

A scanner is an input device that converts physical documents into digital format. It cannot contract or transmit computer viruses. Viruses are typically spread through infected storage media (floppy disks), email attachments, downloads from the internet, or network connections. Scanners only read input and don't execute programs.

The sum of protons and neutrons in an atom's nucleus is called the atomic mass number or mass number. This number represents approximately the atom's total mass since protons and neutrons each have about 1 atomic mass unit. Atomic number refers only to protons, while P/N factor and 'big number' are not scientific terms.

A healthy adult at rest typically breathes 12-16 times per minute, making 12 breaths per minute the correct answer. This respiratory rate is considered normal and is controlled by the body's respiratory center in the brainstem. Rates of 5 or 30 times per minute would be abnormally slow or fast, while 20 times per minute is slightly elevated.

Africanized honey bees, commonly called 'killer bees,' are a hybrid species that originated in Africa. They are known for their aggressive behavior compared to European honey bee subspecies.

A firecracker explosion involves combustion reactions that produce new substances (gases, light, heat), making it a chemical change. Chopping, melting, and boiling are physical changes that don't create new chemical substances.

Mercury, being the innermost planet, is always close to the Sun in our sky and is most visible during twilight hours (just after sunset or just before sunrise). Ancient observers called it the 'morning star' when seen before sunrise.

Impulse is the product of force and the time interval during which the force acts (J = F × Δt). Momentum is mass times velocity (p = mv), while acceleration is force divided by mass (a = F/m).

Nitrous oxide (N2O), commonly known as laughing gas, is the correct answer. It's a colorless, non-flammable gas with a slightly sweet odor that can induce laughter and euphoria when inhaled. Nitrogen dioxide is a toxic brown gas, carbon oxide is not a standard chemical name (carbon monoxide or carbon dioxide are), and ammonium oxide is not a stable compound.

The sartorius muscle is the longest muscle in the human body, running from the hip to the knee diagonally across the thigh. It's responsible for flexing, abducting, and laterally rotating the hip. Options A (Femur - a bone, not a muscle), B (Biceps - upper arm muscle), and C (latissimus dorsi - back muscle) are all incorrect.