Assertion (A) : The length, breadth and height of an open cuboid are 10 cm, 12 cm and 6 cm respectively. If the thickness is 1 cm, then internal dimensions are 8 cm, 10 cm and 5 cm respectively.

Reason (R) : If l, b and h are the external dimension of an open cuboid of thickness 'x', then its internal dimension are (l - 2x), (b - 2x) and (h - x) respectively.

1. Both A and R are correct, and R is the correct explanation for A.

2. Both A and R are correct, and R is not the correct explanation for A.

3. A is true, but R is false.

4. A is false, but R is true.

Assertion (A) : Three solid silver cubes of side 6 cm, 8 cm and 10 cm are melted and recasted into a single solid cube. The side of the new cube = 2 times the side of the smallest cube.

Reason (R) : Volume of cuboid = (l x b x h) cubic units.

1. Both A and R are correct, and R is the correct explanation for A.

2. Both A and R are correct, and R is not the correct explanation for A.

3. A is true, but R is false.

4. A is false, but R is true.

Assertion (A) : If radius of a right circular cylinder is double and the height is reduced to $\dfrac{1}{2}$ of the original, the ratio of volume of new cylinder thus formed to the volume of the original cylinder is 1 : 1.

Reason (R) : Volume of a cylinder = πr²h where r is the radius of the circular base and h is height.

1. Both A and R are correct, and R is the correct explanation for A.

2. Both A and R are incorrect.

3. A is true, but R is false.

4. A is false, but R is true.

A cuboid is 8 m long, 12 m broad and 3.5 m high. Find its

(i) total surface area

(ii) lateral surface area