<span>The problem has to do with oxidation states of the matter. The oxidation state of oxygen will always be -2 with the exception of peroxides which will have a state of -1. The overall balanced state of chemical compounds will be 0, so the oxidation state of Mn in MnO2 will be +4. The oxidation state of MnO4- will then be +7 to balance out to the negative one charge. The state change from +4 to +7 is 3, thus three electrons have to be lost in order for this to happen; a loss of a charge of -3 results in an increase of charge of 3. Oxidation is always the process of 'losing' electrons.
</span><span>E] MnO2(s) MnO4-(aq</span>
Gneiss is a sedimentary rock and granite is a metamorphic rock.
<h3>What are rocks?</h3>
Rocks are geological hard materials that are made up of various types which include:
- Sedimentary rocks: These are rocks that made up of various layers formed from sediments. Example is the gnesis.
- Metamorphic rocks: These are rocks that are form from pre existing rocks that undergoes some transformation. Example is granite
Therefore, Gneiss is a sedimentary rock and granite is a metamorphic rock.
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Chromium is a metal in nature. So when one chromium is
bonded to another chromium, there is a weak intermolecular forces which helds
them together which we call as “metallic bonding”.
Metallic bonding is the intermolecular force of attraction which
exist between valence electrons and the metal atoms. It is considered as the
sharing of various detached electrons between many positive ions, whereby the
electrons serve as a "glue" which gives the substance a definite
structure.
The answer would be D Heterogeneous
