Sodium chloride solution also called normal saline solution which is safe to inject intravenously has a concentration of:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(= 0.9\%\, \ (m/v)\)
Normal saline is the sodium chloride solution that is isotonic with the fluid inside blood cells, so no osmosis takes place and the cells neither gain nor lose water.
Why the other options are incorrect
Option (2) > 0.9% (m/v) — Incorrect. A more concentrated (hypertonic) solution draws water out of the cells, and they shrink.
Option (3) < 0.9% (m/v) — Incorrect. A less concentrated (hypotonic) solution lets water flow into the cells, and they swell and may burst.
Option (4) = 9% (m/v) — Incorrect. Ten times the isotonic concentration; this is strongly hypertonic and would make the cells shrink.
NCERT (2026-27 edition):
Osmosis and Osmotic Pressure – …
