Answer:
B. materials change their properties.
Explanation:
In a chemical change, materials often change their properties because a re-arrangement of atoms takes place.
A chemical change is one in which new kind of matter is formed.
It is always accompanied by energy changes.
- Chemical changes are not reversible.
- They lead to the production of new kinds of matter
- It involves mass changes
- Requires considerable amount of energy
Knees and elbows are two of the most common ones.
It was the element of aluminium where they predict their properties <span />
Moles of oxygen = 22g / 32 (Mr of O2)
Moles of oxygen = 0.7 moles (1 dp)
Avogadro's constant = 6.02×10^23 particles per mole
0.7 moles×(6.02×10^23) = Answer
This is assuming it wants O2, if it wants pure oxygen then replace 32 with 16.
