Question

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

Answer 1

Correct Answer: 4

To determine the number of metal ions that can be characterized by a flame test, we need to know which of the given ions produce characteristic colors upon heating in a flame.

Analysis of Each Metal Ion:

• Sr²⁺: Produces a bright red flame.
• Ba²⁺: Produces a green flame.
• Ca²⁺: Produces an orange-red flame.
• Cu²⁺: Produces a blue-green flame.
• Zn²⁺: Typically does not produce a distinct color in a flame test.
• Co²⁺: Produces a blue flame.
• Fe²⁺: Produces a yellow-green flame, but is less distinctive and often masked by other colors.

Summary of Metal Ions with Characteristic Flames: Characteristic colors are seen with Sr²⁺, Ba²⁺, Ca²⁺, Cu²⁺.

Counting those that yield distinct flame colors: Sr²⁺, Ba²⁺, Ca²⁺, Cu²⁺

Thus, the total number of metal ions characterized by flame tests from the list is: 4