What is a reduction reaction? A. A reaction in which an atom forms a new isotope by gaining neutrons.
B. A reaction in which charged particles form an ionic compound.
C. A reaction in which negatively charged particles are in the products.
D. A reaction in which an atom has gained 1 or more electrons.

D. A reaction in which an atom has gained 1 or more electrons.

Explanation:

The oxidation reduction reactions are called redox reaction. These reactions are take place by gaining or losing the electrons and oxidation state of elements are changed.

Oxidation:

Oxidation involve the removal of electrons and oxidation state of atom of an element is increased.

Reduction:

Reduction involve the gain of electron and oxidation number is decreased.

Consider the following reactions.

4KI + 2CuCl₂  →   2CuI  + I₂  + 4KCl

The oxidation state of copper is changed from +2 to +1 so copper get reduced by gaining the one more electron

answer: the figure is attached herewith.

step-by-step explanation:   we are given to sketch a unit circle and label the terminal points corresponding to

in the attached figure, we have drawn a unit circle, with centre at o(0,0) and radius 1 unit. we have labelled the points a, b, c, d and e corresponding to the angles below

∠aox = 60°,

∠box = 120°,

∠cox = 180°,

∠dox = 240°,

∠eox = 300°.

and the coordinates are a(0.5,1), b(-0.5,1), c(-1,0), d(-0.5,-1) and e(0.5,-1).

thus, the answer is complete.

a. a primary source combines several different accounts of an event. b. a primary source generally benefits from having been written after an event.

explanation: