Which of the following values is written in proper scientific notation?

• A. 7.0 \times 10^{-2}
• B. 3.2 \times 10^4
• C. 0.45 \times 10^3
• D. 12.0 \times 10^2

Answer: (B)

Verified step by step guidance

1. Recall that proper scientific notation expresses a number as \(a \times 10^{n}\), where \(a\) is a number greater than or equal to 1 and less than 10, and \(n\) is an integer exponent.
2. Examine each given value to see if the coefficient (the number before \(\times 10^{n}\)) is between 1 and 10.
3. For \$7.0 \times 10^{-2}$, the coefficient is 7.0, which is between 1 and 10, so this is proper scientific notation.
4. For \$3.2 \times 10^{4}$, the coefficient is 3.2, which is also between 1 and 10, so this is proper scientific notation.
5. For \$0.45 \times 10^{3}\( and \)12.0 \times 10^{2}$, the coefficients 0.45 and 12.0 are not between 1 and 10, so these are not written in proper scientific notation.