Multiple choice

The horizontal rows of elements in a modern periodic table are called _______ and the vertical rows of elements in a periodic table are called _______.

  1. periods, groups

  2. groups, periods

  3. lanthanides, actinides

  4. actinides, lanthanides

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A Correct answer
Explanation

The horizontal rows of elements in a modern periodic table are called periods and the vertical rows of elements in a periodic table are called groups. There are total 7 periods and 18 groups in modern periodic table.