Question

how might the world be different if elements did not combine to form compounds?
the world would be very different - life could not exist.
the world would not exist.
the world would be almost the same as we have.

Explanation:

Life as we know it depends on compounds. For example, water ($H_2O$) is essential for many biological processes. Without compounds, complex molecules like DNA (which has elements like carbon, hydrogen, oxygen, nitrogen, and phosphorus combined) could not exist. However, the world (as in the physical planet) itself could still exist as elements can exist in their pure form (e.g., oxygen gas $O_2$, gold $Au$). So life could not exist but the world (planet) would still be there.

Answer:

The world would be very different - life could not exist.