The correct answer is D. Elements are created that differ from the reactants.. Because in a eeaction, the product is different than the reactants. Take NaCl for example.
They give a double displacement reaction where the ions switch places and give sodium nitrate (NaNO3) and silver chloride (AgCl) as the products. Silver nitrate is also very soluble in water, but silver chloride is highly insoluble in water and will precipitate out of solution as a white solid.
Answer : The most likely happens during this reaction is, Oxidation-reduction
Explanation :
The balanced reaction will be,
In this reaction, neutral iron loses 3 electrons and oxidizes in (+3) state, 
and neutral oxygen gains 2 electrons and reduces in (-2) state,
When iron react with oxygen gas to give iron oxide. This process is known as iron rusting. During the reaction, oxidation-reduction process occurs.
Oxidation : It is a type of chemical reaction in which a substance loses its electrons. Or we can say that in oxidation, the oxidation number increases.
Reduction : It is a type of chemical reaction in which a substance gains its electrons. Or we can say that in reduction, the oxidation number decreases.
Magma and lava are words that are used in relation to rock formation. Magma refers to melted rock, that is rock in liquid form, which is found in the earth's crust. The lava on the other hand to the magma which has escaped from the earth crust and has moved to the surface via volcano vent. Thus. magma and lava both refer to molten rock, but magma refers to the molten rock that is found underneath the earth while lava refer to the molten rock that is found on the earth surface; that is the difference between them.
Explanation:
if it was meant for [Ar]4s²3d¹ :
1s²2s²2p⁶3s²3p⁶4s²3d¹
number of e‐ : 21
atomic number is 21.. element is scandium
ion: Sc³+
