General Science MCQs – Page 92 (Q911-920)

Non-stick cookware is commonly coated with a slippery synthetic material widely known by the popular brand name Teflon, chemically known as polytetrafluoroethylene, or PTFE, a durable synthetic polymer notable for its exceptionally low surface friction and strong overall chemical resistance to virtually anything sticking to it. Teflon was actually discovered largely by accident in 1938 by chemist Roy Plunkett while he was conducting unrelated research on entirely different refrigerant gases, and its distinctive extremely low-friction, non-stick properties subsequently made it genuinely ideal for coating cooking pans and various other practical everyday applications requiring a similarly slippery, non-adhesive surface.

Velcro fasteners work by using two complementary strips of specially designed material that reliably connect together through a simple mechanical mechanism involving tiny hooks on one strip that securely catch onto tiny corresponding loops present on the other matching strip, creating a surprisingly strong yet still easily and quickly separable overall connection. Swiss engineer George de Mestral invented Velcro in 1941 after noticing how small, spiky plant burrs stubbornly stuck persistently to both his clothing and his dog's fur following a country walk, and he subsequently spent several years carefully studying and deliberately replicating this same clever natural hook-and-loop mechanism in a durable synthetic material.

A typical ballpoint pen dispenses ink onto paper mainly using a small rotating ball located precisely at its writing tip, which continuously rotates smoothly as it moves across the paper's surface, evenly picking up ink from an internal ink reservoir on one side and depositing that same ink cleanly onto the paper on the opposite side as the ball steadily rotates during normal writing use. This clever, simple, and remarkably reliable rotating-ball mechanism, first successfully patented in a practical, usable form by Laszlo Biro in 1938, provides notably more consistent, even ink flow compared to earlier traditional fountain pens, while also being significantly less prone to leaking or smudging during ordinary everyday use.

A vacuum, or thermos, flask keeps its contents hot or cold for extended periods mainly by minimizing heat transfer through its specially designed double-walled construction, with a substantial vacuum, essentially empty space largely devoid of air, maintained carefully between its two separate walls. Since heat transfer through simple conduction and convection genuinely requires the presence of some kind of physical medium, such as air or another material, to actually occur, this deliberately created vacuum layer effectively and significantly minimizes both of these particular common heat transfer mechanisms, while the flask's reflective inner surface additionally helps further reduce any remaining heat loss through thermal radiation as well.

Polarized sunglasses lenses are specially designed mainly to reduce glare from reflective horizontal surfaces, such as water, snow, or a smooth road surface, by specifically filtering out the strongly horizontally polarized light waves that are characteristically produced when ordinary unpolarized sunlight reflects directly off these particular flat, reflective surfaces. Polarized lenses achieve this targeted filtering effect by incorporating a specially designed chemical filter aligned to selectively block light waves vibrating in the horizontal direction while still readily allowing vertically oriented light waves to pass through relatively unobstructed, significantly improving overall visual comfort and clarity, particularly for activities like driving or fishing near open water.

Barcode scanners typically read a printed barcode by directing a beam of light, often generated by a small laser, across its surface and then carefully detecting the resulting pattern of reflected light from its distinctive alternating dark bars and lighter spaces, since the darker bars notably absorb more incoming light while the lighter spaces between them instead reflect proportionally more light back toward the scanner's sensor. This detected pattern of varying light and dark reflected light intensity is then converted into a corresponding sequence of electrical signals that a connected computer system can subsequently interpret as a specific numerical code, reliably and rapidly identifying a specific product or item.

Bluetooth is a common, widely used short-range wireless technology that allows various electronic devices, such as headphones, speakers, and smartphones, to communicate directly with one another using radio waves, typically operating over a functional range of up to about 10 meters and specifically designed for convenient short-range communication between devices that are already reasonably close together. Named after a tenth-century Scandinavian king, Harald Bluetooth, who was historically known for successfully uniting several separate warring Danish tribes together, the technology itself was similarly and deliberately designed to help unify and effectively connect different otherwise incompatible electronic devices and communication protocols together.

In computing, a bit is generally considered the most basic, fundamental unit of digital information, representing a single simple binary value of either 0 or 1, corresponding directly to one of two possible distinct electrical states, off or on, within a digital electronic circuit or storage device. All digital data ultimately processed and stored by computers, including text, images, video, and audio, is fundamentally represented and encoded using specific, carefully structured combinations of these extremely simple binary bits, and the very term bit itself is actually a deliberately shortened contraction of the two words binary digit.

In standard computing terminology, a group of eight individual bits is generally referred to as a byte, a fundamental, standardized unit commonly used to conveniently measure both digital data storage capacity and, separately, overall data transmission rates. A single byte can represent exactly 256 distinct possible different values, ranging numerically from 0 up to 255, which is sufficient range to represent a single standard text character using common encoding standards like ASCII, and larger, more practical storage units like kilobytes, megabytes, gigabytes, and terabytes are all subsequently built up as successively larger multiples of this same fundamental byte unit.

In a computer system, the Central Processing Unit, commonly abbreviated as CPU, is often referred to as the brain of the computer, since it is specifically responsible for actually carrying out and executing the vast majority of a computer's core processing instructions, including performing detailed logical operations, mathematical calculations, and coordinating the overall flow of data between various other different connected computer components. Modern CPUs contain many millions, or even billions, of extremely tiny electronic transistors densely packed together, and CPU processing speed, commonly measured in gigahertz, indicates how many individual basic processing cycles the CPU can reliably complete every single second.