Final answer:
The number 5.24×105 contains three significant figures. These include the digits 5, 2, and 4, as the exponential part of the number does not contribute to the significant figure count.
Step-by-step explanation:
The number 5.24×105 has three significant figures. Significant figures are all the digits in a number that carry meaning contributing to its accuracy. This includes all non-zero digits, any zeros between non-zero digits, and any trailing zeros in a decimal quantity.
In the number 5.24×105, the digits 5, 2, and 4 are significant. The exponential part of the number (105) does not affect the count of significant figures. Therefore, the correct answer is 3 significant figures (option b).