In the modern periodic table, how many elements are present in Group 18, the noble gas group commonly discussed in school level chemistry?

Introduction / Context:
The periodic table is organised into groups (vertical columns) and periods (horizontal rows). Group 18 is the noble gas group, which includes chemically inert gases used in many applications. This question checks knowledge of how many elements belong to Group 18 in the typical school level modern periodic table. Knowing the members of Group 18 helps in understanding trends in reactivity, valence electrons, and uses of noble gases.

Given Data / Assumptions:

• We are using the modern long form periodic table.
• Group 18 is the noble gas group.
• At school level, the commonly discussed noble gases are helium, neon, argon, krypton, xenon, and radon.
• Superheavy elements such as oganesson may not be emphasised in basic curricula.

Concept / Approach:
Group 18 elements are characterised by having complete valence electron shells, which makes them very stable and mostly chemically inert. The standard noble gases traditionally listed are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). These six elements occupy the Group 18 positions from period 1 through period 6. While a seventh member, oganesson, has been discovered, in many school level treatments the focus remains on the six classic noble gases.

Step-by-Step Solution:

Verification / Alternative check:
To verify, one can draw or consult a modern periodic table and visually inspect Group 18. Starting from the top of the column: helium in period 1, neon in period 2, argon in period 3, krypton in period 4, xenon in period 5 and radon in period 6. Counting them confirms that there are six noble gas elements traditionally included. Although a superheavy element called oganesson with atomic number 118 is also placed in Group 18, its chemistry is highly specialised and often not included in introductory discussions, so the answer remains six in the context of school examinations.

Why Other Options Are Wrong:

• 5: This would omit one of the recognised noble gases and does not match the periodic table.
• 7: This could be argued only if oganesson is counted explicitly along with the six traditional noble gases, but most basic curricula focus on six.
• 2: This would only account for helium and neon and ignores the others.
• 8: There is no basis for eight noble gases in Group 18 in the modern table.

Common Pitfalls:
Students may be confused by recent discoveries of superheavy elements and think that every group must always have seven or eight entries. Others may mix up the group number with the number of elements in the group. A simple way to avoid mistakes is to memorise the list of noble gases and count them, rather than guessing based on group numbering.

Final Answer:
There are 6 commonly studied elements in Group 18 of the modern periodic table.