JAMB Chemistry 2023 Objective — Question 17

Question 17 of 40 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2023 Objective paper, with the correct answer and a full explanation.

When water is added to anhydrous cobalt(ii) chloride (COCl₂), the colour changes from

A. Blue to white
B. White to blue
C. Blue to pinkCorrect
D. Pink to white

Explanation

Anhydrous CoCl₂ is blue. When hydrated (water added), it turns pink/red: CoCl₂ + 6H₂O → CoCl₂·6H₂O (pink). Anhydrous CuSO₄ changes white → blue on hydration.

Sign up free to unlock

Score tracking
Practice history
Saved questions
Progress dashboard
Personalized sessions
Weak-topic breakdown

…and/or go further with premium services and No Ads.

Create free account

More questions from Chemistry 2023 Objective More Chemistry past papers