Pure water has a freezing point of 0 degrees centigrade but seawater has a lower freezing point because of the salt (NaCl)
Answer:
The nucleus of an atom consists of Protons and Neutrons.-A.
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,
<h2>
Answer:</h2>
ZINC
<h2>
Explanation:</h2>
<em>To identify the element based on the informartion given, we have to find the molar mass since this mass is unique to each element.</em>
Molar mass = mass ÷ moles
<em>We already know the mass based on the question, as such we now need to find the # of moles.</em>
Since 1 mole contains 6.02214 × 10²³ atoms
then let x moles contain 4.19 × 10²³ atoms <em>(given in the question)</em>
<em> </em><em> </em> ⇒ x = (4.19 × 10²³ atoms × 1 mol) ÷ 6.02214 × 10²³ atoms
x = 0.69577 mol
<em>Now that we have the moles we can substitute it into the molar mass equation and solve for the molar mass.</em>
⇒ molar mass = 45.6 g ÷ 0.69577 mol
⇒ molar mass ≈ 65.54 g/mol
This molar mass is closest to that of ZINC.
