The blanks are filled below:

(i) {2, 3, 4} ⊂ {1, 2, 3, 4, 5}

Since, 2, 3, 4 comes in the second set.

(ii) {a, b, c} ⊄ {b, c, d}

Since, ‘a’ is not in the second set.

(iii) {x : x is a student of Class XI of your school}⊂{x : x student of your school}

Since, x is a part of the school too.

(iv) {x : x is a circle in the plane} ⊄ {x : x is a circle in the same plane with radius 1 unit}

Since, first set has no fixed radius circles whereas the second set has only circles with radius 1 unit

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

Since, set 1 has triangle whereas set 2 has rectangle.

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

Since, equilateral triangle is a type of triangle itself.

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

Since, all the even natural numbers are a type of integers.