Answer: (3) molecules have different molecular structures.
Explanation:
1) Oxygen (O₂) and ozone (O₃) are allotropes of each other.
2) Allotropes are different structural forms of a same element with different structures and properties, when they are in the same state: solid, liquid, gas.
3) The bonds is what define the structure and properties of the substances, so since O₂ has only two bonds and O₃ has three bonds, the properties and behaviors of the element are different.
4) Other example of allotropes are graphite and diamond: two different forms of carbon. Both, graphite and diamond are formed only by carbon atoms, but they are bonded differently so, as you know, diamond and graphite have different properties: graphite is very soft while diamond is one of the hardest known substances.
Answer:
exothermic reaction
Explanation:
If there is a drop in temperature, then energy was lost to the surroundings because temperature is the average measure of kinetic energy. An exothermic reaction would result in this lost of energy. An endothermic reaction would absorb energy and make the temperature rise.
30. mixture of compounds
31. compound
32. element
33. compound
34. compound
34. mixture of elements and compounds
