In advertising and display technology, which chemical element is commonly used to produce bright flashing lights in colourful advertising signs and neon tubes?

Introduction / Context:
Bright, glowing tubes and flashing signs have been used for decades to attract attention to shops, cinemas, and restaurants. Many of these signs are popularly known as neon signs. The glowing effect is produced by passing an electric discharge through a gas at low pressure inside a glass tube. General science questions often ask which element is used in such bright advertising signs, helping learners connect chemical elements with real life applications.

Given Data / Assumptions:
- The question refers to bright flashing advertising signs and lighted tubes.
- It asks which element is used inside these signs.
- The options include neon, helium, mercury, and radon.
- We assume the classic glass tube signage commonly seen in city streets and shop windows.

Concept / Approach:
Neon is a noble gas that glows with a characteristic reddish orange light when an electric current passes through it in a discharge tube. This property made neon ideal for use in illuminated advertising signs, and such signs are commonly referred to as neon signs. Helium is also a noble gas but is mostly used in balloons and sometimes in special lamps, not as widely in advertising tubes. Mercury vapour is used in fluorescent lamps, where the light is mainly ultraviolet and converted to visible light by phosphor coatings. Radon is a radioactive gas and is not used in commercial advertising signs because of safety concerns. Therefore, neon is the correct element associated with bright flashing advertising signs.

Step-by-Step Solution:
Step 1: Recall the common term neon sign used for glowing advertising boards. Step 2: Remember that neon gas emits a bright reddish orange glow in electric discharge tubes. Step 3: Compare this with helium, which glows differently and is better known for filling balloons. Step 4: Note that mercury vapour is associated with fluorescent lighting, not typical coloured advertising tubes. Step 5: Exclude radon because it is radioactive and unhealthy for such uses, confirming neon as the answer.

Verification / Alternative check:
Physics and chemistry textbooks often describe discharge tubes filled with different gases and mention neon as the classic example used in signage. Photographs of neon signs show the characteristic orange red glow. Modern advertising signs may also use other noble gases and mixtures to get colours like green or blue, but the general term neon sign persists, reinforcing the link between neon and advertising tubes. This consistent association across textbooks and everyday language supports neon as the correct element.

Why Other Options Are Wrong:
- Helium is mainly used in balloons and some special lamps and is not the classic gas for bright advertising tube signs.
- Mercury is used in fluorescent lights, where ultraviolet radiation excites a phosphor coating; it is not itself the main gas in neon style advertising tubes.
- Radon is radioactive and dangerous, so it is never used for commercial advertising lighting.

Common Pitfalls:
Learners might confuse fluorescent tubes in offices with decorative neon signage and assume mercury is used everywhere. Others may only recall that helium and neon are both noble gases and guess randomly. A good strategy is to remember the everyday phrase neon lights and neon signs, which directly points to neon gas. When a question mentions bright flashing advertising signs, this association should immediately suggest neon as the correct answer.

Final Answer:
The element used in bright flashing advertising signs is Neon.