How do you know if an element is held together by bonds?

Which compound contain an iron with a 3+ charge

How many liters of oxygen gas, at standard temperature and pressure, will react with 35.8 grams of iron metal? 4 fe (s) + 3 o₂ (g) → 2 fe₂o₃ (s)

The diagram below shows the different phase transitions that occur in matter. which arrow represents the transition in which dew is formed?