Which of the following elements in Group 13 has the highest melting point?
Boron
Aluminum
Gallium
Indium
The melting point of the Group 13 elements generally decreases down the group, except for thallium which has a lower melting point than indium. So, among the options given, indium has the highest melting point.
Option (A) is incorrect because Boron has a very high melting point compared to the other non-metals, but it is much lower than the melting points of aluminium, gallium, and indium.
Option (B) is incorrect because Aluminum has a lower melting point than indium.
Option (C) is incorrect because Gallium has a lower melting point than indium.