Consider set A as

A = {1, 2, 3, 4, 5}

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Empty set is the subset of all sets
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Subset is a set which contains all elements of the other set

Since empty set has no elements,

it will be the subset of every set

∴ ϕ ⊂ A

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Set is the subset of itself
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Since, all elements of A are in A,

A is a subset of A

∴ A ⊂ A