Everyday Science

The patella, commonly known as the kneecap, is a bone located in the leg. It protects the knee joint and aids in leg movement.

Saliva contains the enzyme amylase, which begins the digestion of starch by breaking it down into simpler sugars. It does not digest proteins, lipids, or fats.

Vitamin E is chemically known as tocopherol. The other options correspond to different vitamins: Calciferol is vitamin D, Riboflavin is vitamin B2, and Phylloquinone is vitamin K1.

Diabetes mellitus is a metabolic disorder characterized by impaired insulin production or action, leading to abnormal metabolism of glucose and other nutrients. Therefore, it affects the metabolic system.

Photography works by capturing light reflected from objects onto a photosensitive surface or sensor, which forms an image. It does not involve capturing souls, which is a metaphorical or fictional idea.

Vitamin B-9 is commonly known as Folate. It plays a crucial role in DNA synthesis and repair, making option B the correct answer.

The quality rating of diesel fuel is measured by its cetane number, which indicates the combustion speed and ignition quality of the fuel. Octane rating is used for gasoline, not diesel.

Mercury is commonly known as quicksilver due to its silvery appearance and liquid state at room temperature, which allows it to move quickly like a liquid metal.

The quantity of ozone in the atmosphere is commonly measured in Dobson Units (DU), which represent the thickness of the ozone layer if compressed to standard temperature and pressure. The other options are unrelated units or terms.

Presbyopia is a condition where the eye loses the ability to focus on close objects due to aging. Bifocal lenses have two distinct optical powers to correct both near and distant vision, making them suitable for presbyopia correction.

Vitamin B-12 is known as Cobalamin because it contains the metal cobalt in its structure, which is unique among vitamins. This distinguishes it from other B vitamins such as B-1 (Thiamine), B-3 (Niacin), and B-9 (Folic acid).

Water stored in a dam possesses potential energy due to its elevated position above the base level. This energy can be converted into kinetic energy when the water flows down, but the energy possessed while stored is potential energy.

A mercury thermometer is most suitable for measuring the boiling point of water because mercury has a high boiling point (357°C) and remains liquid over the temperature range needed to accurately measure water's boiling point (100°C). Other thermometers like alcohol or liquid crystal thermometers have lower boiling points or are less precise for this purpose.

Cirrus clouds are the highest clouds in the atmosphere, typically found above 20,000 feet. Cirrocumulus and cirrostratus clouds also occur at high altitudes but generally not higher than cirrus clouds. Therefore, the correct answer is Cirrus.

Caustic soda, also known as sodium hydroxide, is widely used in the manufacture of soap through the saponification process, where it reacts with fats and oils to produce soap.

The most abundant element in seawater is chlorine, primarily present as chloride ions. Although sodium is abundant as well, chlorine is present in a higher proportion in seawater.

Vitamin B-2 is known as Riboflavin. It plays a key role in energy production and the metabolism of fats, drugs, and steroids.

Carbon monoxide is a toxic gas that is hazardous to humans because it binds with hemoglobin in the blood, reducing oxygen transport. Carbon dioxide is not toxic at typical environmental levels, and the options 'Lease particles' appears to be a typo, while 'Carbon particles' are harmful but less directly toxic than carbon monoxide.

Pure water has a neutral pH of 7, but natural water typically ranges from slightly acidic to slightly basic, commonly between 6.5 and 8.5, depending on dissolved minerals and environmental factors. Therefore, option D correctly reflects the typical pH range of water.

The Earth revolves around the Sun at an average orbital speed of approximately 29 kilometers per second, which is the widely accepted scientific value.

The Earth's atmosphere is composed of approximately 78% nitrogen, making option C the correct answer. This is a well-established scientific fact about atmospheric composition.

The drum of a Photostat machine is coated with selenium because selenium is a photoconductive material, which means it conducts electricity when exposed to light, making it ideal for the photocopying process.

Gasoline is the primary fuel used in light petrol engines due to its high volatility and suitable combustion properties, making it ideal for light patrol (petrol) engines. The other options are either heavier fuels or not commonly used in such engines.

Strong winds pose the greatest risk to air travel as they can cause turbulence, affect aircraft control during takeoff and landing, and lead to dangerous flying conditions. While clouds, rainfall, and fogs can affect visibility and comfort, strong winds have a more direct impact on flight safety.

A kilowatt-hour (kWh) is a unit of energy, representing the amount of energy consumed when a power of one kilowatt is used for one hour. It is not a unit of power, current, or time.