The standard form of a number 0.000035 is - \( \begin{array}{ll}\text { (a) } 3.5 \times 10^{-3} & \text { (b) } 3.5 \times 10^{-2} \\ \text { (c) } 3.5 \times 10^{-5} & \text { (d) } 3.5 \times 10^{-7}\end{array} \)

To convert the number 0.000035 into standard form, you first need to express it as a number between 1 and 10 multiplied by a power of ten. Here, 0.000035 can be rewritten as 3.5 multiplied by \(10^{-5}\), since moving the decimal point five places to the right gives you the original number. So, the correct answer is (c) \(3.5 \times 10^{-5}\). When thinking about standard form, it's useful to remember it’s all about clarity. This notation isn’t just helpful in math class – it’s often used in science and engineering to handle very large or very small numbers easily, making it a vital skill in various fields such as physics, chemistry, and finance!