Question

Pick out the incorrect statement/s about noble gases. (1) 'He' cannot be used in preference to nitrogen \(\left(\mathrm{N}_{2}\right)\) to dilute the oxygen in the gas cyclinders used by divers. (2) 'He' is used in weather balloons and airships. (3) 'He' is used in cryoscopy to obtain the very low temperatures required for superconductivity and lasers. (4) 'Ar' is used in metallurgical processes. (a) 1 and 3 (b) 2 and 3 (c) 1 and 4 (d) 1 only

Short answer

The incorrect statement is 1 only.

Step-by-step solution

Analyze Statement 1

Statement 1 claims that helium (He) cannot be used to dilute oxygen in gas cylinders for divers. However, helium is commonly used for this purpose because it does not dissolve in body fluids as much as nitrogen, reducing the risk of nitrogen narcosis.

Analyze Statement 2

Statement 2 states that helium (He) is used in weather balloons and airships. This is correct because helium is lighter than air and non-flammable, making it ideal for lifting purposes.

Analyze Statement 3

Statement 3 suggests using helium (He) in cryoscopy for superconductivity and lasers. This is true, as liquid helium is used to achieve extremely low temperatures needed for superconductivity.

Analyze Statement 4

Statement 4 claims that argon (Ar) is used in metallurgical processes. This is correct because argon is often used as a shielding gas in welding to protect the metal from oxidation.

Identify Incorrect Statements

From analyzing each statement, Statement 1 is incorrect, as helium is indeed used to dilute oxygen for divers. Statement 3 is correct, so the incorrect statements are Statement 1 only.

Key concepts

Helium in Diving

Helium plays a crucial role in the world of diving, specifically in deep-sea diving. At high pressures underwater, gases like nitrogen can dissolve into divers' bloodstreams. This can cause a dangerous condition known as nitrogen narcosis, leading to impaired judgment or even unconsciousness. By replacing nitrogen with helium in breathing gas mixtures, divers greatly reduce these risks.

• Helium is less soluble in body fluids than nitrogen, making it a safer choice for deeper dives.
• It reduces the density of the breathing gas, making it easier for divers to breathe under high pressure.
• The mixture of oxygen and helium is often called Heliox, supporting safe and efficient diving.

Helium's properties make it indispensable for creating a breathable atmosphere in the high-pressure environment of deep seas.

Helium in Weather Balloons

In meteorology, helium is the gas of choice for inflating weather balloons. Weather balloons are used to measure atmospheric conditions high above the Earth's surface, providing valuable data for weather forecasting. There are several reasons helium is preferred over other gases for this purpose:

• Helium is lighter than air, which allows the balloon to ascend much higher than it would with a heavier gas.
• Unlike hydrogen, another light gas, helium is non-flammable, adding an essential layer of safety.
• Being inert, helium does not react with other substances it contacts in the upper atmosphere.

These properties make helium an ideal and reliable choice for aiding in understanding and predicting weather patterns.

Cryoscopy and Helium

Helium is essential in achieving the extremely low temperatures required for cryoscopy, a technique used in various advanced technological applications. Helium, especially in its liquid form, is known for maintaining temperatures near absolute zero (around -273°C). This is crucial for studies in superconductivity and for functioning some lasers.

Why Liquid Helium?

• As one of the only liquids with a boiling point near absolute zero, liquid helium provides an unparalleled cooling capacity.
• It enables the observation of phenomena that occur only at these exceedingly low temperatures.
• Industries and scientific facilities utilize it for critical cooling in equipment such as MRI machines and particle accelerators.

By allowing scientists and engineers to cool equipment to these ultralow temperatures, helium plays a key role in modern technology and research.

Argon in Metallurgical Processes

In the world of metallurgy, argon serves an important purpose in the production and processing of metals. Argon is a noble gas, meaning it is largely non-reactive with other elements. This quality makes it an excellent choice for use as a shielding gas in numerous metallurgical processes, particularly welding.

Uses of Argon

• Argon provides an inert atmosphere, preventing metabolic reactions such as oxidation and enhancing the quality of the weld.
• The gas protects the molten metal from harmful contaminants in the atmosphere such as moisture and oxygen.
• It helps in maintaining the stability of the welding arc, contributing to a smooth and controlled welding process.

Argon's unique properties make it invaluable in ensuring the integrity and purity of metalworking processes.