Please choose the correct answer to the question: Which of these is one similarity of the elements in the first group of the periodic table?

Answer1: The elements in the group have similar atomic masses. Answer2: The elements in the group have the same number of electrons. Answer3: The elements in the group are very unreactive metals. Answer4: The elements in the group react with oxygen in similar ways.

Answer format: answer1/answer2/answer3/answer4