Sun spots were first observed by which among the following?

Parthenocarpy is the development of fruits without fertilization, resulting in seedless fruits. Common examples include bananas and some varieties of grapes and oranges widely preferred in commercial agriculture.

When sodium bicarbonate (NaHCO₃), also known as baking soda, is heated, it decomposes and releases carbon dioxide gas (CO₂). The reaction also produces sodium carbonate and water, which is why baking soda is widely used in baking and fire extinguishers.

Guglielmo Marconi successfully transmitted radio signals over long distances and is widely recognized as the pioneer of practical wireless communication. His experiments laid the foundation for modern radio, television, and wireless technology.

Most enzymes are proteins that act as biological catalysts in living organisms. They speed up chemical reactions necessary for digestion, metabolism, respiration, and many other cellular activities without being consumed themselves.

Vitamin D deficiency causes rickets in children, leading to weak and soft bones due to improper calcium absorption. In adults, a similar condition called osteomalacia can occur, causing bone pain and weakness.