(i) {2, 3, 4} ⊂ {1, 2, 3, 4, 5}

∵ 2, 3, 4 ∈ {1, 2, 3, 4, 5}

(ii) {a, b, c} ⊄ {b, c, d}

∵ a ⊄ {b, c, d}

(iii) {x: x is a circle in the plane} ⊄ {x: x is a circle in the same plane with radius 1 unit}. Because there exists a circle having a radius other than 1 unit.

(iv) {x: x is a student of 1 PUC of your college} ⊄ {x: x is a student of your college}

∵ Every student of I PUC is a student of the college.

(v) {x: x is a triangle in a plane} ⊄ {x: x is a rectangle in the plane.

∵ Triangle is not a rectangle.

(vi) {x: x is an equilateral triangle in a plane} ⊂ {x: x is a triangle in the same plane}.

∵ Every equilateral triangle in a plane is a triangle in the same plane.

(vii) {x : x is an even natural number} ⊂ {x : x is an integer}

∵ Every even natural number is an integer.