Everyday Science

Convex lenses are used in microscopes because they converge light rays to form a magnified image of small objects, which is essential for microscopic observation. Concave lenses diverge light and are not used for magnification in microscopes.

Milk is a rich source of Vitamin B-12, which is primarily found in animal-based foods. Cashew nuts, apples, and watermelon do not contain significant amounts of Vitamin B-12.

Lingxi-03, developed by Galaxy Space, was launched using the Long March-3D carrier rocket, which is a commonly used Chinese launch vehicle for such satellites. The other options are either incorrect or non-existent rockets.

A1C measures the average blood sugar level over the past two to three months by assessing the percentage of glycated hemoglobin in the blood, making option B correct.

The troposphere is the lowest layer of Earth's atmosphere where most weather phenomena occur. It lies below the stratosphere, mesosphere, and thermosphere.

Permanent hardness in water is caused by dissolved salts like calcium sulfate and magnesium sulfate, which cannot be removed by boiling. Adding washing soda (sodium carbonate) precipitates these salts, thus removing permanent hardness.

Oxalic acid solution is commonly used to remove rust stains from cloth because it reacts with the iron oxide (rust) and helps dissolve it, making it easier to wash out. Alcohol and kerosene oil are not effective for removing rust stains.

Most meteors burn up in the mesosphere due to friction with atmospheric particles, preventing them from reaching the Earth's surface.

The Solar Corona is the outermost layer of the Sun's atmosphere and mainly consists of extremely hot ionized gases (plasma), not molten lava, ice, or cosmic rays.

The ozone layer is located in the stratosphere, which is the second major layer of Earth's atmosphere. It absorbs most of the Sun's ultraviolet radiation, protecting living organisms.

Some species of parrots are known to keep blind snakes in their nests. These snakes help by feeding on insects and parasites, creating a mutually beneficial relationship.

The Snellen Chart is a chart with letters arranged in multiple rows of decreasing size, used to measure visual acuity during an eye test. The other options are unrelated to eye testing.

Fog consists of tiny liquid water droplets suspended in air, which is a gas. Therefore, it is an example of liquid dispersed in gas.

Cheetahs are known for their incredible acceleration, reaching speeds up to 100 km/h in about 3 seconds, making option A correct.

The moon's surface temperature varies widely due to the lack of atmosphere, ranging from about -173°C at night to 127°C during the day, making option A correct. Other options are either inaccurate or incorrect.

Graphite is commonly used as a dry lubricant due to its layered structure that allows easy sliding between layers, reducing friction. Silica, iron oxide, and diamond are not typically used as lubricants.

Scientific observations from NASA's Lunar Reconnaissance Orbiter and other missions have conclusively established the presence of water ice primarily in the permanently shadowed regions (PSRs) of the Moon's southern polar craters. These regions remain extremely cold and never receive direct sunlight, allowing ice to persist for billions of years. While some ice has been detected in the northern polar regions, it is patchier and less extensive. There is no conclusive evidence of ice presence at the lunar equator. Therefore, the correct answer is 'Southern pole region' (Option A). The option 'All of the above' is incorrect because the equator does not have confirmed ice deposits.

Blood sugar levels are commonly measured in milligrams per deciliter (mg/dL), which indicates the concentration of glucose in the blood. This is the standard unit used in most medical settings.

Since the invention of refrigerators, four major types of gases have been commonly used as refrigerants: ammonia, sulfur dioxide, chlorofluorocarbons (CFCs), and hydrochlorofluorocarbons (HCFCs). This makes option C (4) the correct answer.

Magenta is a color that appears as a reddish-purple hue, created by mixing red and blue light. It is distinct from black, white, or yellow, making option D the correct choice.

The Moon has a large, circular impact basin called the Imbrium Basin, which is one of the largest and most prominent lunar basins. The other options are either misspelled or incorrect names.

The term 'white coal' is commonly used to refer to hydroelectricity because it is a clean and renewable source of energy derived from water, analogous to how coal is a traditional energy source. This nickname highlights hydroelectricity's role as a natural and sustainable energy alternative.

Pearls are primarily composed of aragonite (a crystalline form of calcium carbonate) and conchiolin, an organic protein that binds the crystals together. This composition gives pearls their characteristic luster and structure.

Rainbows are formed when sunlight passes through water droplets in the atmosphere, which act like prisms. These droplets refract, reflect, and disperse the light into its constituent colors, creating a spectrum visible as a rainbow.

The ozone layer is located in the stratosphere, which is the second major layer of Earth's atmosphere above the troposphere. It absorbs most of the Sun's ultraviolet radiation.