Question

Which of the following options is not correct?

• A. $2.300+0.02017+0.02015=2.340$
• B. $126,000$ has $3$ significant figures
• C. $15.15\mu s=1.515\times {10}^{-5}s$
• D. $0.0048=48\times {10}^{-3}$

Answer 1

The correct option is D $0.0048=48\times {10}^{-3}$

$2.300+0.02017+0.02015=2.3432$

Rule: The result of an addition or subtraction is reported to the same number of decimal places as present in number with the least decimal places.

Since the least precise number is $2.300$ and that has three digits after the decimal, therefore the result of the above addition is rounded off to three decimal figures as $2.340$.

$126,000$ has 3 significant figures as zeros are not counted

$15.15\mu s=15.15\times {10}^{-6}s=1.515\times {10}^{-5}s$

$0.0048=4.8\times {10}^{-3}$

Hence, the correct option is $\text{D}$.