Grade 7 Periodic Table Quiz

The correct answer is "At least and only one capital letter." This is because chemical symbols for elements are typically written using one capital letter, such as "H" for hydrogen or "O" for oxygen. While some symbols may consist of two letters, the first letter is always capitalized and the second letter is lowercase, such as "Na" for sodium or "He" for helium. Therefore, the statement "At least and only one capital letter" accurately describes the convention for writing chemical symbols.

Salt has a chemical formula of NaCl, which indicates that it is composed of two elements: sodium (Na) and chlorine (Cl). A compound is a substance made up of two or more different elements chemically combined in a fixed ratio. Since salt is made up of sodium and chlorine in a fixed ratio of 1:1, it is considered a compound.

The compound is a substance composed of two or more elements chemically bonded together. NaCl (sodium chloride), HCl (hydrochloric acid), and CO2 (carbon dioxide) are all compounds because they consist of different elements bonded together. Cl, on the other hand, is not a compound because it represents a single element, chlorine, which is not chemically combined with any other element.

Carbon has 6 electrons. This is because the atomic number of carbon is 6, which indicates the number of protons in its nucleus. In a neutral atom, the number of electrons is equal to the number of protons. Therefore, carbon has 6 electrons.

An atom of the element with atomic number 6 always has 6 protons in its nucleus. The atomic number of an element represents the number of protons in its nucleus, and since the question specifically mentions the element with atomic number 6, it indicates that it is referring to carbon (C). Therefore, every carbon atom will have 6 protons in its nucleus.

The innermost energy level, also known as the first shell or K-shell, can hold a maximum of 2 electrons. This is because the first shell has only one sublevel, which is the s sublevel, and the s sublevel can accommodate a maximum of 2 electrons.

Nobel gases contain inert (non-reactive) elements. These elements have a full outer electron shell, which makes them stable and less likely to react with other elements. They are called "noble" gases because their stable electron configuration is similar to the configuration of the noble gases helium, neon, argon, krypton, xenon, and radon. Due to their non-reactivity, noble gases are often used in various applications, such as lighting, cryogenics, and as inert atmospheres in laboratories.

The atomic mass tells us the combined mass of both protons and neutrons in an atom. It does not include the mass of electrons, as they have a negligible mass compared to protons and neutrons. Therefore, the correct answer is "The number of protons and neutrons."

Sugar is a solute because it is the substance that is being dissolved in a solvent. In a solution, the solute is the substance present in a smaller amount, while the solvent is the substance present in a larger amount. In this case, sugar would be dissolved in a solvent such as water to form a sugar solution. Acetone, water, and egg white, on the other hand, can act as solvents in certain situations but are not considered solutes in this context.

Group 1 metals, also known as alkali metals, are known for their high reactivity and the formation of stable compounds. This is because they have only one valence electron, which they readily lose to form a stable octet configuration. As a result, they react vigorously with nonmetals, such as halogens and oxygen, to form ionic compounds with high stability. Their reactivity increases down the group due to the decreasing ionization energy and increasing atomic radius. Therefore, the answer "high reactivity and the formation of stable compounds" accurately describes the characteristic properties of Group 1 metals.