Because magnesium and copper will not produce a hydroxide.
Number 3. c.
Number 4. a.
Number 5. d.
Explanation:
1 Cal of energy is equivalent to 4.184 Joules.
A.
770Cal of energy = 3221.680 joules
Therefore, 780kCal of energy = 3221680 Joules.
B.
3200000 Joules (in 2 s.f).
C.
I000 joules = 1 kJoule
3221680 joules = 3221.689 kJoules.
D.
3200 kJ (in 2 s.f).
Oxidation is when a substance gains oxygen molecules. For example when hydrogen reacts with oxygen it forms H₂O. The H₂ has been oxidised.