Correct Option
Salts of certain elements, particularly alkaline earth metals, are crucial for imparting distinct colours to fireworks through the phenomenon of flame emission. When heated, the electrons in these metal atoms become excited and jump to higher energy levels. As they return to their ground state, they emit light at specific wavelengths, which are perceived as characteristic colours.
- Strontium salts (e.g., strontium nitrate, strontium carbonate) are primarily responsible for producing a vibrant red colour.
- Barium salts (e.g., barium nitrate, barium chlorate) are used to generate a distinct green colour.
These salts are essential components in pyrotechnic compositions, not only for their characteristic colouration but also for their role in stabilizing the chemical reactions.
Incorrect Options
- Zinc and sulphur: Sulphur acts as a fuel and reducing agent in fireworks compositions, contributing to the combustion process. Zinc is sometimes used to produce smoke effects or contribute to spark effects, but neither zinc nor sulphur salts are primarily responsible for imparting vivid flame colours.
- Potassium and mercury: Potassium compounds, such as potassium nitrate or potassium perchlorate, are commonly used as oxidizers in fireworks, facilitating the combustion of fuels. Mercury and its compounds are highly toxic and are not used in modern fireworks due to safety concerns.
- Chromium and nickel: Salts of chromium and nickel are not typically used to produce distinct, vibrant flame colours in fireworks. While some metal compounds can contribute to spark effects or enhance certain aspects of the display, they do not provide the primary colouration like strontium or barium.