Question

Assertion (A): Two cubes each of edge length 10 cm are joined together.
The total surface area of newly formed cuboid is 1200 cm².

Reason (R): Area of each surface of a cube of side 10 cm is 100 cm^2.

Options

• Both Assertion (A) and Reason (R) are true. Reason (R) is the correct explanation of Assertion (A).

• Both Assertion (A) and Reason (R) are true. Reason (R) does not give correct explanation of (A).

• Assertion (A) is true but Reason (R) is not true.

• Assertion (A) is not true but Reason (R) is true. 

Answer 1

Assertion (A) is not true but Reason (R) is true. 

Explanation:

Given Edge of cube = 10 cm

In cube Length = Breadth = Height 

When join two cube New length is 20 cm,

height = 10 cm,

width = 10 cm

It convert in cuboid

Total surface Area of cuboid = 2(lb + bh + hl)

= 2[20 × 10 + 10 × 10 + 10 × 20]

= 2[200 + 100 + 200]

= 2[500]

= 1000 cm

Assertion is wrong.

Reason: Area of each surface = 10 × 10 cm² 

= 100 cm² 

Reason is true but not the correct explanation of assertion.