Everyday Science

A lactometer is an instrument used to measure the specific gravity (density) of milk, which helps determine its purity and quality. It is not used for ships or honey.

As altitude increases, the temperature generally decreases due to the thinning atmosphere and lower air pressure, which causes air to cool.

Thomas Edison is widely credited with inventing the practical and commercially viable incandescent light bulb, which revolutionized electric lighting.

Vitamin A is found in animal-based foods like milk, eggs, butter, cheese, cream, and liver (option A), as well as in plant-based foods rich in beta-carotene such as broccoli, apricots, cantaloupe, carrots, sweet potato, and spinach (option C). Therefore, both A and C are correct sources of Vitamin A.

One mile is exactly 1609.34 meters, which is the standard conversion used internationally.

Commercial aircraft usually fly in the troposphere, which is the lowest layer of the atmosphere where most weather phenomena occur and where air density is suitable for flight. The stratosphere is higher up and typically not used for commercial flights.

Leather is primarily made from collagen, a structural protein found in animal skin and connective tissues, which is processed to create leather.

The 'bar' is a unit of pressure, commonly used to measure atmospheric pressure. It is not a unit of temperature, heat, or electric current.

The central color of a rainbow is green, which appears in the middle of the visible spectrum between blue and yellow. This is why green is considered the central color in the sequence of rainbow colors.

Diabetes is primarily caused by a lack of insulin or the body's inability to use insulin effectively. Insulin is a hormone that regulates blood sugar levels, so its deficiency leads to diabetes.

Convex mirrors are used in automobiles because they provide a wider field of view, allowing drivers to see more area behind and beside the vehicle, which enhances safety.

Sunlight takes approximately 8 minutes and 20 seconds to travel from the Sun to the Earth, covering a distance of about 150 million kilometers at the speed of light.

Only about 1% of the world's water is used for drinking purposes, as the majority is used for agriculture, industry, and other needs. This makes option A the correct answer.

The density of ice is approximately 917 kg/m³, which is less than the density of liquid water (1000 kg/m³). This lower density is why ice floats on water.

Wind moves from areas of high pressure to areas of low pressure due to the pressure gradient force, which causes air to flow from higher to lower pressure regions.

The melting point of ice is 0°C, which is the temperature at which ice changes from solid to liquid under standard atmospheric pressure.

Kilohertz (kHz) is a unit of frequency equal to 1,000 cycles per second, commonly used to measure electromagnetic radio wave frequencies.

Glucose syrup is primarily made from maize (corn) starch, which is hydrolyzed to produce glucose. This is a common industrial process for producing glucose syrup.

A microphone converts sound energy (mechanical vibrations in the air) into electrical signals, which can then be amplified, recorded, or transmitted. This is the fundamental working principle of microphones.

Iodine deficiency leads to the enlargement of the thyroid gland, known as goiter, because iodine is essential for thyroid hormone production. The other options are caused by different deficiencies: anemia by iron deficiency, scurvy by vitamin C deficiency, and rickets by vitamin D deficiency.

Protein is essential for growth because it provides the building blocks (amino acids) needed for the development and repair of body tissues. While minerals, vitamins, and carbohydrates are important for overall health and energy, protein directly supports growth.

Normal rain is slightly acidic because carbon dioxide from the atmosphere dissolves in rainwater and reacts with water to form a weak acid called carbonic acid, which lowers the pH slightly below neutral.

The sun appears oval near the horizon because its light rays are refracted differently at various angles as they pass through Earth's atmosphere, causing the vertical dimension to be compressed more than the horizontal, resulting in an oval shape.

Glass is primarily made from silica, which is found in sand, combined with other silicates to form the glass mixture. This makes option C the correct answer.

The density of air at standard temperature and pressure (around 15°C and 1 atm) is approximately 1.225 kg/m³, making option C the correct choice.