Concept: The question tests on the basics of Counting
The 5 subjects can be allotted to 6 periods in 6C5 = 6C1 = 6 ways. These 5 subjects can then be arranged in 5! = 120 ways.
The 6th period can be allotted any 1 subject in 5 ways.
Therefore the total number of ways = 6 * 120 * 5 = 3600 ways