In fireworks, which chemical element or its compounds are mainly responsible for producing a green coloured flame?

Introduction / Context:
Fireworks display brilliant colours due to the presence of specific metal salts that emit characteristic colours when heated. Understanding which element produces which colour is a common general science and chemistry question. In particular, green flames are strongly associated with compounds of certain metals. This question checks whether you can correctly link the green colour in fireworks to the element barium.

Given Data / Assumptions:

• The question asks which element (or its compounds) produces a green flame in fireworks.
• Options include sodium, potassium, barium, mercury, and None of the above.
• We assume standard pyrotechnic formulations used in festival and display fireworks.

Concept / Approach:
Different metal salts emit different colours in a flame test because their electrons absorb and re emit energy at specific wavelengths. Sodium salts produce a bright yellow flame, potassium salts give a lilac or light violet colour, and barium salts are well known for their green emission in pyrotechnics. Mercury is not used for colour effects in fireworks due to its toxicity and other issues. Therefore, barium is the correct element for green flames.

Step-by-Step Solution:
Step 1: Recall the basic flame test colours from chemistry: sodium gives yellow, potassium gives lilac, and barium gives green. Step 2: Fireworks use similar principles but with more complex mixtures to intensify these colours. Step 3: Green colours in fireworks are typically produced by barium salts such as barium nitrate or barium chlorate. Step 4: Confirm that sodium based fireworks would appear yellow or golden, not green. Step 5: Conclude that barium is the element responsible for the green flame, making it the correct option.

Verification / Alternative check:
Chemistry textbooks and reference charts for flame tests consistently list barium compounds as giving a green flame. Pyrotechnic guides similarly mention barium compounds as key ingredients for green fireworks. Sodium and potassium have well documented but different colours, while mercury is avoided due to toxicity and is not a normal colourant in fireworks. These multiple sources align with the choice of barium as the correct answer.

Why Other Options Are Wrong:
Sodium: Produces a bright yellow flame, which is used for golden or yellow effects but not green. Potassium: Produces a lilac or pale violet flame, not the vivid green seen in some fireworks. Mercury: Toxic and not used as a standard colour producing element in fireworks. None of the above: Incorrect because barium, the correct element, is already present in the options.

Common Pitfalls:
Some students might guess sodium simply because it is the most familiar metal from salt, or potassium because they have seen its flame test. Others might overthink the question and choose None of the above. To avoid these mistakes, it helps to memorise a short mapping: sodium–yellow, potassium–lilac, barium–green, and strontium–red. This makes colour based questions about fireworks and flame tests easy to answer.

Final Answer:
In fireworks, the green coloured flame is mainly produced by compounds of barium.