Pre-IB Grade 9 Science Practice Exam

Noble gases are a group of elements whose outer electron shells are full, giving them great stability and making them very unreactive. This full valence shell means they don’t easily gain, lose, or share electrons, so they don’t form compounds under normal conditions. They sit in Group 18 of the periodic table, and their atoms are typically monatomic gases at room temperature. The statement that best describes them is that they are a family of nonreactive nonmetals found in group 18 of the periodic table, which captures both their lack of reactivity and their position on the table. The other ideas aren’t right for this description: saying something about the outermost electrons alone doesn’t define noble gases, calling them an alloy would describe a mixture of metals, and claiming they form covalent bonds goes against their usual behavior of not bonding readily.