Question

which reactions are redox reactions?
check all that apply.
□ \\(\ce{zn(s) + fe^{2+}(aq) -> zn^{2+}(aq) + fe(s)}\\)
□ \\(\ce{ca(s) + cl2(g) -> cacl2(s)}\\)
■ \\(\ce{ba(no3)2(aq) + k2so4(aq) -> baso4(s) + 2kno3(aq)}\\)
■ \\(\ce{hcl(aq) + naoh(aq) -> h2o(l) + nacl(aq)}\\)

Explanation:

Step1: Check for oxidation state changes

Redox reactions involve changes in oxidation states.

Step2: Analyze first reaction

Zn(s) (0) → Zn²⁺(aq) (+2, oxidation); Fe²⁺(aq) (+2) → Fe(s) (0, reduction). Change occurs.

Step3: Analyze second reaction

Ca(s) (0) → Ca²⁺ in CaCl₂ (+2, oxidation); Cl₂(g) (0) → Cl⁻ in CaCl₂ (-1, reduction). Change occurs.

Step4: Analyze third reaction

All ions retain oxidation states: Ba²⁺, NO₃⁻, K⁺, SO₄²⁻. No change.

Step5: Analyze fourth reaction

All ions retain oxidation states: H⁺, Cl⁻, Na⁺, OH⁻. No change.

Answer:

A. Zn(s) + Fe²⁺(aq) → Zn²⁺(aq) + Fe(s), B. Ca(s) + Cl₂(g) → CaCl₂(s)