Why do small pellets of sodium hydroxide become wet when left exposed?
Answer and explanation
Correct answer: They absorb moisture from air
Sodium hydroxide is strongly hygroscopic and also deliquescent: it attracts water vapour from the atmosphere and can dissolve in the absorbed moisture. When its pellets are left exposed, they therefore become moist, sticky or apparently wet. This behaviour is a physical absorption process, not the creation of water or conversion into oxygen. Sodium hydroxide pellets do not normally release chlorine merely because they are exposed to air. Hence option A is correct.
Frequently asked questions
What is the correct answer to this question?
They absorb moisture from air
Why is this the correct answer?
Sodium hydroxide is strongly hygroscopic and also deliquescent: it attracts water vapour from the atmosphere and can dissolve in the absorbed moisture. When its pellets are left exposed, they therefore become moist, sticky or apparently wet. This behaviour is a physical absorption process, not the creation of water or conversion into oxygen. Sodium hydroxide pellets do not normally release chlorine merely because they are exposed to air. Hence option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
