Question

Identify use of argon from following.

• A. In supersonic wind tunnels
• B. For magnetic resonance imaging
• C. For producing inert atmosphere in welding
• D. For production of lasers

Hint:

Remember that Argon's primary commercial value lies in its chemical "laziness" (inertness) combined with its high abundance in air (around 0.93%), making it the default economic option whenever a process requires an unreactive gas blanket.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The problem states that the formation of NO₂ from N₂ and O₂ is endothermic and asks for the corresponding sign of ΔH.

Step 2: Key Formula or Approach:
An endothermic reaction absorbs heat from the surroundings, which thermodynamically corresponds to a positive enthalpy change (ΔH>0).

Step 3: Detailed Explanation:
Since the synthesis of NO₂ gas requires an input of energy, the enthalpy of the system increases. Therefore, the change in enthalpy (ΔH) for this process is greater than zero.

Step 4: Final Answer:
For an endothermic process, ΔH>0, which is represented by option (D).