Which of the following element has lowest atomic number?

Option 1 : B

CONCEPT:

• In the Modem Periodic Table, the arrangement of elements is based on their increasing atomic number in the horizontal rows.
• The Modem Periodic Table is used to predict the properties of elements.
• It is divided into 18 groups ​(vertically) and 7 periods (horizontally).
• According to their shared physical and chemical properties, the elements can be grouped into the major categories of metals, metalloids and nonmetals.

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EXPLANATION:

• From the above periodic table, the atomic numbers of B, Al, Ga are 5, 13, 31 and 49 respectively.
• The lowest atomic number is 5 i.e; B.

So, option 1^st is correct.