(O level Chem) Are reactions of acids redox reactions?

Acids and Alkalis is one of the easiest chapters to many students. The basic thing is that acids are substances that produce protons H⁺(aq) or hydroxonium ions H₃O⁺ when dissolved in water, not in alcohol or any other solvents. Do get the habit of writing “H⁺(aq)” instead of just “H⁺” because the proton is simply too unstable by itself. Because the concentration of H⁺(aq) in the acidic solutions is greater than the concentration of OH^-(aq), acidic solutions turn blue litmus to red, and yellow methyl orange to red. They have a pH (= -lg [H⁺]) of less than 7.

The properties of acids are due to their protons. 

H⁺(aq) ions are also responsible for the various properties of acids. They combine with OH^-(aq) in alkalis to produce water. This gives the general equation, acid + alkali --> salt + water, that's a neutralization. Its ionic equation is H⁺(aq) + OH^-(aq) --> H₂O(l). Note that the salt, which is soluble, don't appear in the ionic equation because they are spectator ions.

Acids can also be neutralized by carbonates. Carbonates are compounds that contain the ion CO₃^2-. Carbonates are either soluble such as Na₂CO₃ (Remember that all sodium compounds are soluble.) or insoluble such as CaCO₃ (in limestone) and CuCO₃. Effervescence is observed during the neutralization of an acid by a carbonate. The colorless gas gives a white precipitate with limewater indicating that it's carbon dioxide. The general equation is acid + carbonate --> salt water + carbon dioxide. The ionic equation is H⁺(aq) + CO₃^2-(aq) --> H₂O(l) + CO₂(g).

Acids also corrode metals producing a colorless and odorless gas that extinguishes a burning splint with a “pop” sound. The general equation for the reaction is acid + metal --> salt + hydrogen. If an acid reacts with zinc, then the ionic equation is Zn(s) + H⁺(aq) --> Zn²⁺(aq) + H₂(g). This is called a displacement reaction because the hydrogen is displaced by the metal. Remember, however, that dilute HCl and H₂SO₄ do not react with copper which is unreactive.

So, are the above three reactions redox reactions? To identify a redox reaction, we look for whether there are oxidation and reduction occurring in the reaction. The best way is to look for changes in oxidation states which are charges of atoms. When there's an increase in oxidation state, we say oxidation has occurred. When there's a decrease in oxidation state, we say reduction has occurred. A redox reaction has to have both oxidation and reduction occurring simultaneously. In the following, the oxidation states of atoms are already calculated for you. You've got to know how to calculate them. Only one of the reactions is a redox reaction. Which one? 

(A Level Chem) A question on synthesizing a ketone from an alcohol

Try this question before you look at a video in which you can find the answers...

2-butanone, a ketone, is synthesized from 2-butanol as follow.
To prepare a solution P of acidified dichromate, a mass of hydrated sodium dichromate Na₂Cr₂O₇.2H₂O is dissolved in dilute sulfuric acid.
To prepare a solution Q of 2-butanol in ethyl ether, ½ mole of 2-butanol is dissolved in ethyl ether.
Solution Q is slowly added to solution P in a flask with stirring. The reaction that occurs is:
3CH3CHOHCH2CH3 + Cr2O7^2- + 8H⁺ --> 3CH3COCH2CH3 +2Cr³⁺ + 7H2O
The flask now contains 2-butanone, Na⁺, Cr³⁺, ethyl ether and water. To obtain the 2-butanone, the reaction mixture is poured from the flask into a separating funnel. The mixture will separate into two layers with the ether layer on top of the aqueous layer. The ether layer should contain most of the 2-butanone because the ketone is more soluble in ether than in water.
Sodium carbonate is added to the ether layer and some carbon dioxide is released. Anhydrous sodium sulfate is then added. As a result, a clear dry mixture of ether and the ketone is obtained. The sodium carbonate and sodium sulfate solids are filtered off.

(a)    Explain what color change would be seen.  

(b)   Calculate the mass of 2-butanol that is dissolved in ethyl ether.

(c)    Calculate the mass of hydrated sodium dichromate used.

(d)   If the actual yield is 30 g, what is the percentage yield?

(e)    Describe how the 2-butanone is extracted from the aqueous layer.

(f)    Why is (i) sodium carbonate (ii) anhydrous sodium sulfate added?

(g)   Explain how 2-butanone and ethyl ether are separated.

After you have gone through some thought processes by attempting the question, watch this great video on how the experiment described in the question is done:

Organic Synthesis