Question

Assertion :Water is tested by using blue cobalt chloride. Reason: Water turns blue cobalt chloride pink.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct, but Reason is not the correct explanation for Assertion.
• C. Assertion is correct, but Reason is incorrect.
• D. Assertion is incorrect, but Reason is correct.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

${CoCl}_4^{2-}+6H_{2}O\left(l\right)\leftrightarrow {\left[Co{\left(H_{2}O\right)}_6\right]}^{2+}+4{Cl}^{-}$

(blue) (pink)

Both assertion and reason are correct because cobalt chloride on reaction with water from hexa aqua complex of cobalt which is pink in colour. Since colour changes from blue to pink on absorbing water on cobalt chloride it is used for testing water.