Given A = {5, 6, 7, 8}. Which one of the following is incorrect?

Given set A = {5, 6, 7, 8}

A. Φ ⊆ A

We know that null set will be subset to every other non-empty set.

So, it’s true

B. A ⊆ A

We know that a set is subset to itself. So, it’s true.

C. {7, 8, 9} ⊆ A

The above set will not be a subset to A because set A didn’t contain element ‘9’. But it contains. So, it is false.

D. {5} ⊂ A

The above set is power set to A because it has same element as in set A and the no. of elements in Set is less than set A. So, it is true.