1.
Argon
Correct Answer
A. Ar
2.
Oxygen
Correct Answer
C. O
Explanation
Oxygen is the correct answer because it is the only element among Na, C, O, and Si that is listed separately from the others. The other elements are listed in pairs, while oxygen is listed alone. Therefore, it can be inferred that the answer is O.
3.
Hydrogen
Correct Answer
A. H
Explanation
The correct answer is H because hydrogen is the chemical element with atomic number 1, represented by the symbol H. It is the lightest and most abundant element in the universe, making up about 75% of its elemental mass. Hydrogen is a colorless, odorless, and tasteless gas, and it is the primary building block of the universe. It is also a key component of water and many organic compounds.
4.
Carbon
Correct Answer
A. C
Explanation
The correct answer is C. Carbon is represented by the symbol C on the periodic table. It is a chemical element with the atomic number 6 and is known for its ability to form a wide variety of compounds due to its unique bonding properties. Carbon is essential for life and is found in all living organisms. It is also a key component in many important substances such as coal, diamonds, and graphite.
5.
Nitrogen
Correct Answer
A. N
Explanation
The correct answer is N because Nitrogen is represented by the chemical symbol N. The other options (H, Ca, P) represent the chemical symbols for Hydrogen, Calcium, and Phosphorus, respectively.
6.
Phosphorus
Correct Answer
A. P
Explanation
The correct answer is P, which stands for Phosphorus. Phosphorus is a chemical element with the symbol P and atomic number 15. It is a highly reactive nonmetal and an essential element for life. It is commonly found in minerals and is vital for various biological processes, such as energy production and DNA synthesis. Phosphorus is also used in fertilizers, detergents, and various industrial applications.
7.
Magnesium
Correct Answer
A. Mg
Explanation
Magnesium is represented by the symbol Mg on the periodic table. It is a chemical element with atomic number 12. Magnesium is a shiny gray solid and is known for its lightness and high strength-to-weight ratio. It is commonly used in alloys and as a component in various industrial applications. Fe represents iron, He represents helium, and H represents hydrogen, none of which match the given symbol Mg. Therefore, the correct answer is Mg.
8.
Sodium
Correct Answer
B. Na
Explanation
The correct answer is Na, which is the chemical symbol for sodium. Sodium is a highly reactive alkali metal that is commonly found in salt compounds. It is an essential element for many biological processes in the human body and is also used in various industrial applications.
9.
Calcium
Correct Answer
A. Ca
Explanation
The correct answer is Ca because the symbol "Ca" represents the chemical element calcium. Calcium is a soft gray alkaline earth metal that is essential for the growth and development of organisms. It is commonly found in bones, teeth, and shells, and plays a crucial role in various biological processes such as muscle contraction, nerve function, and blood clotting. Therefore, "Ca" is the correct symbol for calcium.
10.
Silicon
Correct Answer
A. Si
Explanation
Silicon is represented by the chemical symbol Si. The other elements listed (P, Mg, Ar) do not correspond to the symbol Si, therefore they are not the correct answer.
11.
Aluminum
Correct Answer
A. Al
Explanation
Aluminum is a chemical element with the symbol Al. It is a lightweight, silver-gray metal that is commonly used in various industries due to its low density and high resistance to corrosion. The symbol "Al" represents aluminum in the periodic table of elements. Therefore, Al is the correct answer.
12.
Potassium
Correct Answer
B. K
Explanation
The correct answer is K because potassium is represented by the chemical symbol K.
13.
Iron
Correct Answer
A. Fe
Explanation
Iron is represented by the chemical symbol Fe in the periodic table. Fe is derived from the Latin word "ferrum" which means iron. Iron is a metallic element with atomic number 26. It is commonly used in the production of steel and is known for its strength and durability. Iron is also an essential element for living organisms as it plays a crucial role in the transportation of oxygen in the blood.
14.
Chlorine
Correct Answer
B. Cl
Explanation
Chlorine is represented by the symbol "Cl" in the periodic table. It is a chemical element with the atomic number 17. Chlorine is a yellow-green gas at room temperature and is commonly used for disinfection and water treatment due to its strong oxidizing properties. It is also an essential element for the production of PVC, solvents, and many other industrial products.
15.
Helium
Correct Answer
B. He
Explanation
The correct answer is "He" because "He" is the symbol for the element Helium.