Here is a better translation:
[13] He is the One who constructed the earth and placed on it mountains and rivers. And from the different kinds of fruits, He made them into pairs - males and females. The night overtakes the day. These are solid proofs for people who think.
[15] As for the earth, we constructed it, and placed on it stabilizers (mountains), and we grew on it a perfect balance of everything.
[16] And He placed stabilizers (mountains) on earth, lest it tumbles with you, as well as rivers and roads, that you may be guided.
[21] And we placed on earth stabilizers, lest it tumbles with them, and we placed straight roads therein, that they may be guided.
[27] Who is the One who made the earth habitable, caused rivers to run through it, placed on it mountains, and created a barrier between the two waters? Is it another god with GOD? Indeed, most of them do not know.
[31] He created the heavens without pillars that you can see. He established on earth stabilizers (mountains) lest it tumbles with you, and He spread on it all kinds of creatures. We send down from the sky water to grow all kinds of beautiful plants.
[50] And we created the earth, and scattered on it mountains, and grew in it all kinds of beautiful plants.
[77] We placed on it high mountains, and provided you with fresh water to drink.
[79] He established the mountains
[88] And the mountains and how they are constructed
To know more about the Mountains you can look at this website
http://www.jalyat.net/mountains.htm
So before, you copy and paste from a website, know the facts. Yusuf Ali has many translation errors.