\begin{tabular}{|c|c|}
\hline
tests & observations \\
\hline
\begin{tabular}{l}
Solution [tex]$Y$[/tex] was divided into four portions in four test-tubes. \\
test 1 \\
A strip of universal indicator paper was dipped into the first portion of solution [tex]$Y$[/tex].
\end{tabular}
& the universal indicator paper turned blue \\
\hline
\begin{tabular}{l}
test 2 \\
Aqueous copper(II) sulfate was added to the second portion of solution [tex]$Y$[/tex].
\end{tabular}
& a blue precipitate formed \\
\hline
\begin{tabular}{l}
test 3 \\
A flame test was done using the third portion of solution [tex]$Y$[/tex].
\end{tabular}
& a red flame was seen \\
\hline
\begin{tabular}{l}
test 4 \\
[tex]$2 cm^3$[/tex] of dilute sulfuric acid was added to the fourth portion of solution [tex]$Y$[/tex].
\end{tabular}
& no visible change; the test-tube became slightly warmer \\
\hline
\end{tabular}

(a) Suggest the [tex]$pH$[/tex] of solution [tex]$Y$[/tex].

(b) Identify solution [tex]$Y$[/tex].



Answer :

Let's analyze the information step by step to determine the pH of solution Y and identify what solution Y is.

### Part (a): Suggest the pH of solution Y

Observations:
- Universal indicator paper turned blue.

Analysis for pH:
- Universal indicator paper turning blue is indicative of a basic (alkaline) solution.

Conclusion for pH:
- A basic solution usually has a pH above 7. Based on the observation where the universal indicator paper turned blue, a reasonable suggested pH for the basic solution could be around 8.

So, the pH of solution Y is 8.

### Part (b): Identify solution Y

We'll go through each test and interpret the observations step by step to identify solution Y.

Test 1:
- Universal indicator paper turning blue indicates a basic solution. This means solution Y is not acidic but basic.

Test 2:
- Aqueous copper(II) sulfate added to the solution resulted in the formation of a blue precipitate.
- A blue precipitate with copper(II) sulfate typically indicates the presence of carbonate ions (CO₃²⁻).
- Indicating solution Y has carbonate ions.

Test 3:
- A red flame observed during the flame test.
- A red flame is characteristic of lithium ions (Li⁺).

Test 4:
- Addition of dilute sulfuric acid causing no visible change but slight warming.
- This further confirms the presence of carbonate ions because the reaction between carbonate ions and dilute sulfuric acid produces carbon dioxide (CO₂) and water (H₂O), which might not show visible bubbling but causes slight warming.

Combining all observations:
- Solution Y is a basic solution.
- It contains lithium ions (Li⁺) and carbonate ions (CO₃²⁻).

From these observations, it is reasonable to conclude that solution Y is Lithium Carbonate (Li₂CO₃).

So, the identified solution Y is Lithium Carbonate (Li₂CO₃).