When glaciers are growing larger, the concentration of the heavier oxygen isotope in sea water increases?

TRUE

Explanation: Oxygen has two isotopes namely, ¹⁶O (being the lighter oxygen) and ¹⁸O (being the heavier oxygen). Both this isotopes plays a significant role.

The water-ice that accumulates at the glaciated region are derived from the seas and oceans. The ocean and sea water when heated, gets vaporized and rises up, being rich in ¹⁶O, whereas the ¹⁸O, being the heavier isotope does not get vaporize and so it remains in the oceans.

This lighter oxygen isotopes ¹⁶O are then carried to the atmosphere which subsequently falls back as snow in the glacial covered region and consecutively forms ice undergoing compaction.

This, is the reason why ¹⁶O are rich in the glaciated region, whereas the ocean waters are rich in ¹⁸O.

Thus, the above given statement is true, i.e when glaciers become large in size and quantity, then the concentration of heavier oxygen isotope also increases in the ocean and sea water.

he would use the colour black