Mass of sample in picogram method is ____ gram.

Correct option is B

Correct option: (b) < 10⁻¹² gram
Explanation (why b is correct):
· Picogram (pg) is an extremely small unit of mass.
· 1 picogram = 10⁻¹² gram.
· Therefore, any sample measured by the picogram method must have a mass less than 10⁻¹² gram.
❌ Why other options are incorrect
· (a) 1–10 g
· This is a macroscopic mass, far larger than picogram range.
· (c) 10⁻⁶ – 0.001 g
· This corresponds to microgram to milligram range, not picogram.
· (d) 0.05 – 0.5 g
· Typical laboratory-scale mass, not ultra-trace analysis.
�� Key Points
· Pico (p) = 10⁻¹²
· Picogram methods are used in ultra-trace and advanced analytical techniques.
✔️ Final Answer: Option (b)