A student measures the mass of a sample as 0.00284 kg. Which expression correctly represents this mass in scientific notation with proper SI units?
A2.84 × 10⁻³ kg
B2.84 × 10³ kg
C28.4 × 10⁻⁴ kg
D2.84 × 10⁻² g
Explanation
📌 Move decimal 3 places right: 0.00284 → 2.84 × 10⁻³. Coefficient must satisfy 1 ≤ a < 10, and SI mass unit is kg. Distractor B has wrong exponent sign; C violates scientific notation convention; D uses wrong unit (2.84 × 10⁻² g = 0.0000284 kg, two orders off).