Everyday Science

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.

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.

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.

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.

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

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

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 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.

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.

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.