Chapter 2, Problem 7STP

Interpretation Introduction

Interpretation:

The total amount of time elapsed during the reaction needs to be determined.

Concept introduction:

The precision of a measurement is denoted by the number of digits reported and the reported digits are termed as significant figures. Significant figures include all known digits plus one estimated digit.

Scientific notation can be used to express any number as a number between and (termed as a coefficient) multiplied by raised to a power (termed as an exponent).

Answer to Problem 7STP

Correct answer: The correct option is (d).

Explanation of Solution

Reason for correct option: In order to addition or subtract the numbers which are written in scientific notation, exponents must be the same. When the exponents are same, simply add the coefficients. When the exponents are not same, simply subtract the coefficients.

According to question,

Time taken by the first step $=2.5731\times {10}^2\text{s}$

Time taken by the second step $=3.60\times {10}^{-1}\text{s}=0.00360\times {10}^2\text{s}$

Time taken by the third step $=7.482\times {10}^1\text{s}=0.7482\times {10}^2\text{s}$

Add the time taken by first step, second step and third step to find the answer:

$\text{= 2}{\text{.5731×10}}^{\text{2}}\text{s}\text{+ }0.00360\times {10}^2\text{s}+0.7482\times {10}^2\text{s}$

$\text{=}\text{3}{\text{.3249 ×10}}^{\text{2}}\text{s}$

Hence, the correct option is (d).

Conclusion

As per the calculation correct answer is option (d).