Which is the correct way to represent 0.0035 kg by using scientific notation? –3.5 103 kg –3.5 10–3 kg 3.5 10–3 kg 3.5 103 kg?

It would be

3.5 × 10⁻³ kg.

The decimal point must be moved 3 places to the right in order to have it behind the first non-zero digit; this gives us the exponent of 3, and since we are moving the decimal to the right, it is a negative exponent.