The number of elements present in the third, fourth, fifth, sixth and seventh periods in the modern periodic table is:

Correct option is C

The correct answer is (C)   ​8, 18, 18, 32 and 32, respectively

• Third Period: 8 elements
• Fourth Period: 18 elements
• Fifth Period: 18 elements
• Sixth Period: 32 elements
• Seventh Period: 32 elements

Information booster:

• Third Period: Contains 8 elements (2 from the s-block and 6 from the p-block).
• Fourth Period: Contains 18 elements (2 from the s-block, 10 from the d-block, and 6 from the p-block).
• Fifth Period: Contains 18 elements (2 from the s-block, 10 from the d-block, and 6 from the p-block).
• Sixth Period: Contains 32 elements (2 from the s-block, 14 from the f-block (lanthanides), 10 from the d-block, and 6 from the p-block).
• Seventh Period: Contains 32 elements (2 from the s-block, 14 from the f-block (actinides), 10 from the d-block, and 6 from the p-block).​