Question: 60: The element used for welding metals with high melting points is :
(1) \mathrm{Cl}_{2}
(2) \mathrm{H}_{2}
(3) Ne
(4) He
Answer: Option (2)
Explanation:
Metals with high melting points, such as iron, steel, and tungsten,
require very high temperatures for welding.
Hydrogen gas (\mathrm{H}_{2}) is used as a fuel in oxy-hydrogen torches
because it burns with oxygen to produce an extremely hot flame.
The reaction is :
2\mathrm{H}_{2} + \mathrm{O}_{2} \rightarrow 2\mathrm{H}_{2}\mathrm{O}This reaction releases a flame temperature of about 2800°C,
which is sufficient for welding metals with high melting points.
Other gases like chlorine (\mathrm{Cl}_{2}), neon (Ne),
and helium (He) are either reactive in undesirable ways or inert
and do not produce a flame suitable for welding.
Therefore, hydrogen (\mathrm{H}_{2}) is the correct choice
for welding high-melting-point metals.