What is the best way to write the words in bold in sentence 7? (7) His first major find was discovery of the planet Uranus in 1781

You failed to provide any bold-faced words, so all I can do is correct the sentence as it should be written.

His first major find was the discovery of the planet Uranus in 1781 .

Add the word 'the' and a period as shown. And, technically, if Uranus is already understood to the listener/reader, then the word 'planet' is redundant.

Explanation:

recent brain research has shown some surprising benefits as a result of formal musical training. learning to play a musical instrument appears to develop parts of the brain that can even influence academic results. the studies indicate that the earlier a child begins training, the more benefits there are. one such study showed that children who began musical studies before the age of seven had a more developed brain in the region where language production and auditory processing take place. scientists believe there is mounting evidence to show that early musical training can improve brain function.

explanation:

what excerpt? i would generally think a.