How many groups are present in the modern periodic table?

• A. 20
• B. 7
• C. 18
• D. 12

Answer: (C)

Verified step by step guidance

1. Understand that the modern periodic table is organized into vertical columns called groups, which represent elements with similar chemical properties.
2. Recall that the groups are numbered from 1 to 18, including both the main-group elements and the transition metals.
3. Recognize that the number 7 corresponds to periods (horizontal rows), not groups.
4. Note that the number 20 or 12 do not correspond to the standard count of groups in the modern periodic table.
5. Conclude that the modern periodic table contains 18 groups, which is the correct and widely accepted number.