Which of the following is not alkali?
Correct answer: B. CaO
- A. NaOH
- B. CaO
- C. Al(OH)₃
- D. All of these
Explanation
The correct answer is Option B: CaO. Calcium oxide (CaO) is not an alkali; it is a basic oxide that reacts with water to form calcium hydroxide (Ca(OH)₂), which is an alkali. Sodium hydroxide (NaOH) is a strong alkali, making Option A incorrect. Aluminum hydroxide (Al(OH)₃) is amphoteric and not classified as an alkali, but it can neutralize acids and bases, so it is not the correct answer either. Option D is incorrect because not all listed substances are non-alkalis, as NaOH is clearly an alkali.
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About Acids, Bases and Salts
Acid and base behaviour is explained through the Bronsted-Lowry transfer of protons and the Lewis donation or acceptance of electron pairs. The topic includes pH, pOH, ionisation and water equilibrium, plus salt formation and hydrolysis, where a salt solution may become acidic, basic or neutral.
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