Atoms that have lost or gained one or more electrons are called ions.
Answer:
atoms of isotopes of an element have different numbers of neutrons.
Explanation:
isotopes have the same number of protons, but different numbers of neutrons.
A homogeneous mixture is a mixture that is mixed so well together that you cannot see the different components that make up the mixture as the ingredients will not separate out, even over time.
Answer: The remains of plants and animals are called organic matter.
Explanation:
Answer : The reagent present in excess and remains unreacted is, 
Solution : Given,
Moles of
= 3.00 mole
Moles of
= 2.00 mole
Excess reagent : It is defined as the reactants not completely used up in the reaction.
Limiting reagent : It is defined as the reactants completely used up in the reaction.
Now we have to calculate the limiting and excess reagent.
The balanced chemical reaction is,

From the balanced reaction we conclude that
As, 2 moles of
react with 1 mole of 
So, 3.00 moles of
react with
moles of 
From this we conclude that,
is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Hence, the reagent present in excess and remains unreacted is, 