a) synthesis- or combination- reaction
After finding the oxidation states of atoms, you identify the half reactions (option c).
The half reactions are given by the change of the oxidation states of the atoms.
For example if Cu is in the left side with oxidation state 0 and in the other side with oxidation state 2+, then there you have a half reaction (oxidation reaction). And if you have O with oxidation state 0 in the left side and with oxidation state 2- in the right side, there you have other half reaction (reducing reaction).
Answer:
is the value of the equilibrium constant at this temperature.
Explanation:
Equilibrium constant in terms of partial pressure is defined as the ratio of partial pressures of products to the partial pressures of reactants each raised to the power equal to their stoichiometric ratios. It is expressed as 

Partial pressures at equilibrium:



The equilibrium constant in terms of pressures is given as:


is the value of the equilibrium constant at this temperature.
Answer: The answer is Fossil A is younger than the index fossil.
Explanation: Because it’s the newest layer
the time it take for a planet to rotate on its axis makes up its day so if it were slower the day would be longer like earth, it take about 24 hours to make one full rotation.
Now for a year the distance from its star is the largest factor, because the further out the longer it takes to revolve around it, thus making a longer year.