Question

Assertion (A)
The outer surface of a hemisphere of radius 7 cm is to be painted. The total cost of painting at Rs 5 per cm² is Rs 2300.

Reason (R)
The total surface area of a hemisphere is 3π r².

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is a correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true but Reason (R) is not a correct explanation of Assertion (A).
(c) Assertion (A) is true and Reason (R) is false.
(d) Assertion (A) is false and Reason (R) is true.

Answer 1

(d) Assertion (A) is false and Reason (R) is true.
Assertion (A):
Total surface area of the hemisphere$=3\mathrm{\pi }{r}^2$
$$\begin{gathered} =\left(3\times \frac{22}{7}\times 7\times 7\right){\text{cm}}^2 \\ =462{\text{cm}}^2 \end{gathered}$$

Cost of painting at Rs 5 per cm^{2$=\text{Rs}\left(462\times 5\right)$}

= Rs 2310
Hence, Assertion (A) is false.

Reason (R): The given statement is true.