Question

When is $C{r^{4 + }}$ oxidized to $$C{r^{6 + }}$$, the $C{r^{4 + }}$ ion
A. Loses 2 electrons
B. Loses 2 protons
C. Gains 2 electrons
D. Gains 2 protons
E. Gains 1 neutron

Answer 1

Hint: Oxidation means the loss of electrons. By the following equation you will understand,
$${M^{2 + }} \to {M^{4 + }} + 2{e^ - }$$
In this the metal ‘M’ is oxidised by losing two electrons. Reduction is the reaction which is used to gain electrons. Metals are easily oxidised and non metals are hard to oxidise.

Complete step by step answer:
The equation of oxidation for $C{r^{4 + }}$ion is the following
$C{r^{4 + }} \to C{r^{6 + }} + 2{e^ - }$
Here the chromium ion is changing its oxidation state from +4 to +6 by losing two electrons as it is visible from the equation above.
The other way for finding the electron lost is by finding out the difference in the oxidation number or the charge before and after oxidation. The chromium oxidation number changes from +4 to+6 , so the difference between them is
=6-4
= 2
Therefore the $C{{r}^{4+}}$ion loses 2 electrons.

Hence the option A is the correct one.

Additional Information:
Oxidation occurs when an atom, molecule or an ion loses one or more electrons in a chemical reaction. When oxidation occurs, the oxidation state of the species increases. The meaning of oxidation does not generally mean oxygen is involved in this.
The opposite of oxidation is reduction. This occurs when there is gain of electrons or when the oxidation state of the substance decreases.
The older meaning of oxidation involves when oxygen is added to the compound. This was because oxygen was the first oxidising agent which was known. This process is defined as electron loss and increase in oxidation state. Electrochemical reactions are the example of oxidation reactions. When oxidation and reduction occur simultaneously in the same reaction then it is called redox reaction.

Note: Students generally get confused between oxidation and reduction. They get confused about which process we lose electrons and in which process we gain electrons. So kindly understand the concept and read the question thoroughly. Redox reactions are included in photosynthesis, corrosion, respiration, and combustion.