Everyday Science

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.

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.

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.

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.

Saturn is the least dense planet in our solar system, with an average density lower than water, which means it would float if placed in a sufficiently large body of water. The other planets listed have densities greater than water and would sink.

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.

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.

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.

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.

The Moon has neither a significant atmosphere nor a global magnetic field. It has only a very thin exosphere and localized magnetic anomalies, but no substantial atmosphere or magnetic field like Earth.