Question 6

To find the volume $V = L \times B \times T$, we first convert all measurements to the same unit (cm):

• $L = 10.5$ cm (3 significant figures)
• $B = 0.05$ mm $= 0.005$ cm (1 significant figure)
• $T = 6.0$ $\mu$m $= 6.0 \times 10^{-4}$ cm $= 0.00060$ cm (2 significant figures)

Calculation: $V = 10.5 \times 0.005 \times 0.00060 = 0.0000315$ cm$^3$.

According to the rules for significant figures in multiplication, the result must be rounded to the least number of significant figures found in the factors. The number of significant figures are 3, 1, and 2. The minimum is 1. Rounding $0.0000315$ to 1 significant figure gives $0.00003$ cm$^3$, which is $3 \times 10^{-5}$ cm$^3$. Thus, option (D) is correct.