Question

which sentence is more formal?
a glockenspiel is similar to a xylophone; however, the bars of a glockenspiel are not made of wood but of metal.
a glockenspiel is similar to a xylophone; however, the bars of a glockenspiel arent made of wood but of metal.

Explanation:

In formal writing, the full form of the verb (e.g., "are not") is preferred over contractions (e.g., "aren't"). The first sentence uses "are not" which is more formal, while the second uses the contraction "aren't".

Answer:

A glockenspiel is similar to a xylophone; however, the bars of a glockenspiel are not made of wood but of metal.