Is there any difference between these pairs?

Hello,

I’d like to know if there’s any difference between:

  1. instantly and instantaneously in such a sentence as “They were killed [instantly or instantaneously?].”

  2. pleasing and pleasant in such a sentence as "This kind of music is always [pleasing or pleasant?] to me.

  3. glimpse and glance in such a sentence as “We didn’t even manage to [glimpse or glance?] it.”

Thank you!

Other than that the parts of speech are different, there is no significant difference in the actual meaning of 1 and 2.

Sentence 3 is incorrect with ‘glance it’. It would need to say ‘glance at it’.

glance gaze stare glimpse glare
These are all words for an act of looking, when you turn your eyes in a particular direction.
look = an act of looking at somebody/something:Here, have a look at this.
glance = a quick look:She stole a glance at her watch.
gaze = a long steady look at somebody/something:She felt embarrassed under his steady gaze.
stare = a long look at somebody/something, especially in a way that is unfriendly or that shows surprise:She gave the officer a blank stare and shrugged her shoulders.
glimpse = a look at somebody/something for a very short time, when you do not see the person or thing completely:He caught a glimpse of her in the crowd.
glare = a long angry look at somebody/something:She fixed her questioner with a hostile glare.