General Science MCQs – Page 95 (Q941-950)

Rubber used in manufacturing vehicle tires is generally strengthened and made significantly more durable through vulcanization, a specific chemical process discovered by Charles Goodyear in 1839 that involves heating raw natural rubber together with sulfur, creating strong chemical cross-links between the rubber's individual long polymer chains. This important vulcanization process dramatically improves the rubber's overall elasticity, strength, and resistance to significant temperature changes, transforming otherwise relatively soft, impractical raw rubber into the notably durable, temperature-resistant material genuinely necessary for reliably manufacturing modern vehicle tires and countless other practical rubber products.

The processing speed of a computer's CPU is commonly measured and advertised using the unit gigahertz, indicating specifically how many billions of individual basic processing cycles the CPU's internal clock can reliably complete every single second, with higher gigahertz values generally, though certainly not always exclusively, corresponding to faster overall processing performance. Modern CPU performance actually depends on numerous other significant additional factors beyond simple clock speed alone, including the total number of individual processor cores present and overall architectural efficiency, which is precisely why directly comparing raw gigahertz values alone across genuinely different CPU models or architectures can sometimes prove genuinely misleading.

Among common digital storage units, a gigabyte is generally larger than a megabyte, since digital storage units typically increase by a consistent factor of approximately 1,000, or more precisely 1,024 in strict binary terms, at each successive standard unit level, progressing in order from byte, to kilobyte, to megabyte, to gigabyte, to terabyte, and further on to petabyte and exabyte. Understanding this consistent, standardized progression helps clarify why a single modern gigabyte-capacity storage device can typically hold roughly a thousand times more digital data than an older megabyte-capacity device, a substantial and highly significant practical difference in genuinely usable everyday storage capacity.

A pixel, short for picture element, is generally considered the smallest basic individual unit used to build up digital images and electronic displays, with each individual pixel typically representing one single small point of color information within a much larger overall composed image. A digital image's total resolution is generally determined by the total number of individual pixels it contains, commonly expressed as width multiplied by height, such as a common 1920 by 1080 display resolution, and generally speaking, a greater overall total number of pixels allows for correspondingly finer image detail and improved overall visual clarity when viewing a given digital image or display.

Modern touchscreens on smartphones commonly detect finger touches using either capacitive or resistive touch sensing technology, with capacitive touchscreens, the more common type used in most current modern smartphones, specifically detecting the small electrical charge naturally present in a human finger by measuring corresponding subtle changes in the screen's own underlying electrical field at the specific point of contact. Resistive touchscreens instead work through simple direct physical pressure applied to the screen's surface, and while they can be reliably operated using any object, including a gloved hand or a stylus, they are generally somewhat less precise and responsive overall compared to modern capacitive touchscreen technology.

A typical car engine, known formally as an internal combustion engine, primarily converts the chemical energy stored within its fuel into usable mechanical energy, achieved by igniting a carefully controlled mixture of fuel and air within enclosed engine cylinders, and the resulting rapid, controlled combustion generates expanding, high-pressure gases that forcefully push down on pistons, which subsequently rotate a connected crankshaft to ultimately produce the rotational mechanical power needed to actually drive and move the vehicle forward. This entire combustion-based process inevitably also generates a substantial amount of waste heat as an inevitable byproduct, which is precisely why vehicles require a dedicated cooling system to help prevent dangerous engine overheating during normal operation.

Most modern car engines operate using a repeating combustion cycle generally referred to as the four-stroke cycle, consisting of four distinct sequential phases occurring within each engine cylinder, intake, compression, power, and exhaust, that together repeat continuously in a well-coordinated, precisely timed sequence to reliably generate continuous usable mechanical power. This widely adopted four-stroke design generally offers notably better overall fuel efficiency and lower harmful emissions compared to the simpler alternative two-stroke engine design, which is precisely why the vast majority of modern passenger cars rely specifically on this particular well-established four-stroke combustion cycle for their primary engine operation.

Older refrigerant gases called chlorofluorocarbons, or CFCs, were largely phased out of common industrial and consumer use mainly due to their genuinely harmful, damaging effect on Earth's protective stratospheric ozone layer, since these particular chemical compounds release highly reactive chlorine atoms upon breaking down in the upper atmosphere that can each subsequently destroy many thousands of individual ozone molecules through repeated ongoing catalytic chemical reactions. This significant scientific discovery led directly to the internationally coordinated 1987 Montreal Protocol agreement, which successfully phased out CFC production and use worldwide, and modern refrigerants used today are specifically designed to be considerably less harmful to the vital ozone layer.

Both refrigerators and air conditioners commonly use a mechanical component called a compressor to help circulate refrigerant throughout their sealed internal system and effectively remove unwanted heat from the space being actively cooled, specifically by significantly increasing the refrigerant's pressure and corresponding temperature before it subsequently flows onward to release its absorbed heat outside the cooled space. The compressor essentially serves as the primary driving mechanical force behind the entire cooling cycle, and it typically also happens to be the single largest overall energy-consuming component within most refrigeration and standard air conditioning systems currently in common use.

An air conditioner primarily cools a room by transferring unwanted heat away from the indoor air, using a continuously circulating refrigerant that absorbs heat directly from the warmer indoor air as it evaporates within the indoor unit, and subsequently releases that same absorbed heat outside the building as it condenses back into liquid form within the outdoor unit. This entire process effectively moves existing heat energy from inside the room to outside the building, rather than genuinely creating any cold air directly, and it typically also removes some excess moisture from the indoor air as a welcome secondary side effect, further improving overall indoor comfort levels during hot, humid weather conditions.