How Much Science Do You Know?

Explanation
The molecule symbol for methane is CH4.

Explanation
Dry ice is a form of frozen carbon dioxide. It is called "dry" ice because it does not melt into a liquid when heated, but instead goes through a process called sublimation, where it changes directly from a solid to a gas. Dry ice is commonly used for cooling purposes, such as preserving perishable items during transportation or creating special effects in theater productions.

Explanation
The atmosphere is a mixture of 78% nitrogen, 21% oxygen and 1% other gases.

Explanation
Insulin is produced in the pancreas. The pancreas is an organ located in the abdomen, behind the stomach. It plays a crucial role in regulating blood sugar levels by producing and releasing insulin into the bloodstream. Insulin helps to control the amount of glucose in the blood and allows cells in the body to use and store glucose for energy.

Explanation
Rainfall does not directly affect photosynthesis. Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen. While rainfall indirectly supports photosynthesis by providing plants with the water they need to carry out the process, it is not a direct factor that affects the process itself. Temperature, light intensity, and chlorophyll, on the other hand, directly impact photosynthesis. Temperature affects the rate of chemical reactions involved in photosynthesis, light intensity provides the energy needed for the process, and chlorophyll is the pigment that captures sunlight for photosynthesis to occur.

Explanation
The pH of the stomach is approximately 1-3. This level of acidity is necessary for the stomach to break down food and kill bacteria. The stomach produces hydrochloric acid, which helps in the digestion process. A pH of 1-3 is highly acidic, indicating a low pH level.

Explanation
Sodium is the chemical element with the symbol Na and atomic number 11. It is a highly reactive metal that is commonly found in salt compounds. Sodium is known for its role in maintaining fluid balance in the body and is essential for nerve and muscle function. It is commonly used in the production of various chemicals and is also a component of table salt.

Explanation
Diamonds are a form of the chemical element carbon. Diamonds are composed of carbon atoms that are arranged in a crystal lattice structure, giving them their unique properties such as hardness and brilliance. Carbon is the only chemical element that can form diamonds under the conditions of high pressure and temperature found deep within the Earth's mantle.

Explanation
Graphite is the correct answer because it is the mineral commonly used to make the lead in pencils. Despite its name, pencil "lead" is actually made of graphite, a form of carbon that is soft and easily leaves marks on paper. Graphite is a good choice for pencil lead because it has a layered structure that allows it to easily slide off onto the paper, making it ideal for writing and drawing.

Explanation
The femur is the longest bone in the human body. It is located in the thigh and extends from the hip to the knee. The femur is responsible for supporting the weight of the body and facilitating movement. It is a strong and sturdy bone that plays a crucial role in the structure and function of the skeletal system.