Find out total number of cation(s) that produce precipitate with aqueous solution of `Na_(2)CO_(3)`.
`Cu^(2+)(aq.),Mg^(2+)(aq.),Fe^(3+)(aq.),Pb^(2+)(aq.),Al^(3+)(aq.),Hg^(2+)(aq.),Zn^(2+)(aq.),NH_(4)^(+)(aq.),Cs^(+)(aq.)`

Explanation

To determine the total number of cations that produce a precipitate with an aqueous solution of Na2CO3, we will analyze the solubility of the carbonates formed by the given cations.

**Step 1: Identify the cations provided.**
The cations given in the question are:
- Cu²⁺
- Mg²⁺
- Fe³⁺
- Pb²⁺
- Al³⁺
- Hg²⁺
- Zn²⁺
- NH₄⁺
- Cs⁺

**Step 2: Understand the solubility rules for carbonates.**
According to solubility rules, most carbonates are insoluble in water, with the exception of:
- Alkali metal carbonates (Group 1A)
- Ammonium carbonate (NH₄₂CO₃)

Thus, carbonates of cations from Group 1A (like Na⁺, K⁺) and NH₄⁺ are soluble, while carbonates of other cations are generally insoluble.

**Step 3: Analyze each cation for precipitate formation with Na2CO3.**
- **Cu²⁺**: Forms CuCO3, which is insoluble.
- **Mg²⁺**: Forms MgCO3, which is insoluble.
- **Fe³⁺**: Forms Fe2(CO3)3, which is insoluble.
- **Pb²⁺**: Forms PbCO3, which is insoluble.
- **Al³⁺**: Forms Al2(CO3)3, which is insoluble.
- **Hg²⁺**: Forms HgCO3, which is insoluble.
- **Zn²⁺**: Forms ZnCO3, which is insoluble.
- **NH₄⁺**: Forms (NH4)2CO3, which is soluble.
- **Cs⁺**: Forms Cs2CO3, which is soluble.

**Step 4: Count the cations that produce precipitates.**
From the analysis:
- Cations that produce precipitates (insoluble carbonates): Cu²⁺, Mg²⁺, Fe³⁺, Pb²⁺, Al³⁺, Hg²⁺, Zn²⁺.
- Cations that do not produce precipitates (soluble carbonates): NH₄⁺, Cs⁺.

Thus, the total number of cations that produce precipitates is **7**.

**Final Answer: 7 cations produce precipitate with aqueous Na2CO3.**

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