What is a redox reaction? When a magnesium ribbon burns in air with a dazzling flame and forms white ash, is magnesium oxidized or reduced? Why?

Q. (a) What is a redox reaction? Explain with an example.
(b) When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why?
(c) In the reaction represented by the equation:
${\mathrm{MnO}}_2+4\mathrm{HCl}\underset{}{\to }{\mathrm{MnCl}}_2+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cl}}_2$
(i) name the substance oxidised.
(ii) name the oxidising agent.
(iii) name the substance reduced.
(iv) name the reducing agent.

Q. Statement 1: Magnesium burns in air with a dazzling white flame forming metal oxide.
Statement 2: Metals on reaction with water produce metal oxide along with oxygen.

Q. When magnesium ribbon burns in the air, it forms white ash. The chemical name of white ash is:

Q. When a burning magnesium ribbon is introduced in a gas jar containing oxygen, it will burn with :
(1) a reddish flame
(2) a pale blue flame
(3) a golden yellow flame
(4) a dazzling white flame