Which of the following alkaline earth metals imparts colour to the flame?

The correct answer is option 4.

Concept:

• A flame test is a qualitative analytical method that uses the color the flame changes when the chemical is heated to identify the presence of specific elements, mostly metal ions. 
• The elements in Group 2 of the periodic table are alkaline earth metals. These consist of barium (Ba), radium (Ra), strontium (Sr), calcium (Ca), magnesium (Mg), and beryllium (Be).

Explanation:

1. A common and efficient technique for determining the presence of metal ions in a material is the flame test.
2. The metal ions' electrons are excited by the flame's energy, and as they return to their ground state, they release a distinctive color of light.

• The flame is brick red in hue due to the calcium.
• The flame is colored ruby red by strontium.
• Barium gives the flame a green tint.

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