Question

What is the formula of dinitrogen pentoxide?

Answer 1

`N_2O_5"`

Explanation:

Lets have a look at the words involved:

`di`nitrogen and `pent`oxide.

The `di` and `pent` are common prefixes to words which signify numbers, but which numbers? Have a look at this table, and you will find that in this case they signify 2 and 5 respectively.

https://www.slideshare.net/mlacoursiere/c20-review-unit-01-matter-energy-and-the-periodic-table (Slide 46)
Using this knowledge (note that "penta" has the "a" removed for words starting with a vowel like "oxide"), it is possible to say that there are 2 nitrogen's and 5 oxygen's in this chemical equation, thus `N ""_2O""_5"`

Hope that Helped!
https://www.slideshare.net/mlacoursiere/c20-review-unit-01-matter-energy-and-the-periodic-table