In the periodic table, elements are arranged according to (a) atomic mass (b) number of neutrons (c) number of protons (d) mass number

Step 1: Define the Problem

Identify how elements are arranged in the periodic table.

Step 2: Break Down the Problem

Consider each option:

• (a) Atomic mass
• (b) Number of neutrons
• (c) Number of protons
• (d) Mass number

Step 3: Apply Relevant Concepts

The modern periodic table is organized based on the atomic number, which is the number of protons in an atom's nucleus.

Step 4: Analysis, Verify and Summarize

• Atomic Mass: Earlier versions of the periodic table used atomic mass, but this is not the current standard.
• Number of Neutrons: This does not determine the position in the periodic table.
• Number of Protons: This is the atomic number, which defines the element's position.
• Mass Number: This is the sum of protons and neutrons and is not used for arrangement.

Final Answer

(c) number of protons