Number of metal ions characterized by flame test among the following is Sr^2+, Ba^2+, Ca^2+, Cu^2+, Zn^2+, Co^2+, Fe^2+$$Sr^{2+}, Ba^{2+}, Ca^{2+}, Cu^{2+}, Zn^{2+}, Co^{2+}, Fe^{2+}$$

### Core Logic The flame test is typically used to characterize certain s-block metals (like alkali and alkaline earth metals) and a few transition metals that impart characteristic colors to a Bunsen flame. Evaluating the given ions: 1. Sr^2+$Sr^{2+}$: Crimson red flame. (Yes) 2. Ba^2+$Ba^{2+}$: Apple green flame. (Yes) 3. Ca^2+$Ca^{2+}$: Brick red flame. (Yes) 4. Cu^2+$Cu^{2+}$: Blue-green flame. (Yes) 5. Zn^2+$Zn^{2+}$: No characteristic flame color in standard qualitative analysis. (No) 6. Co^2+$Co^{2+}$: No characteristic flame color. (No) 7. Fe^2+$Fe^{2+}$: No characteristic flame color. (No) ### Step 1: Final Count The metal ions characterized by flame tests are Sr^2+, Ba^2+, Ca^2+$Sr^{2+}, Ba^{2+}, Ca^{2+}$, and Cu^2+$Cu^{2+}$. Total number = 4. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: The s Block Elements Class 12 Chemistry: The d and f Block Elements