Answer: There are 
atoms of hydrogen are present in 40g of urea, 
.
Explanation:
Given: Mass of urea = 40 g
Number of moles is the mass of substance divided by its molar mass.
First, moles of urea (molar mass = 60 g/mol) are calculated as follows.
According to the mole concept, 1 mole of every substance contains 
atoms.
So, the number of atoms present in 0.67 moles are as follows.
In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.
Thus, we can conclude that there are atoms of hydrogen are present in 40g of urea, .
The volume of the 18M HCl needed to make the solution will be 2.5 mL.
<h3>Dilution</h3>
According to the dilution principle, the number of moles of solutes in a solution before and after dilution must remain the same.
Since, mole = molarity x volume
Thus, molarity x volume before dilution = molarity x volume after dilution.
Mathematically, the equation is written as: m1v1 = m2v2
In this case, m1 = 18 M, m2 = 1.5 M, and v2 = 30 mL.
What we are looking for is v1, the amount of the stock HCl needed for dilution.
v1 = m2v2/m1 = 1.5 x 30/18 = 2.5 mL.
Thus, 2.5 mL of the stock HCl would be needed.
More on dilution can be found here: brainly.com/question/21323871
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Answer:
An atom of Bromine (Br) forms an ion and becomes Br⁻
Explanation:
- Atoms of elements gain or lose electron(s) to attain a stable configuration and form ions.
- When an atom gains electron(s) it forms a negatively charged ion called an anion.
- For example, Bromine is a halogen and its atom requires to gain one electron to attain stability and form a bromine ion (Br⁻).
- When an atom loses electron(s) it forms a positively charged ion called a cation.
- For instance, atoms of calcium(Ca) requires to lose two electrons to attain stability and form calcium ion (Ca²⁺).
Diamond is an allotrope of carbon; that just means it is a different crystalline structure, but pure diamond contains only carbon atoms. (unrelated, but interesting - colored diamonds come from impurities like boron and nitrogen in the crystal structure!) The molar mass of carbon is 12.01 g/mol. You can find the molar mass by looking at the periodic table. If you look under number 6, Carbon, you should see the atomic weight right under it: 12.01. The molar mass is this same number, in grams. That means that one mole, or 6.022E23 carbon atoms, weigh 12.01 grams.
<span>But you don't have one mole. You only have 2 grams. </span>
<span>So how many moles do you have? 2 grams out of 12 grams. 2/12 = 1/6 or 0.167. You have 1/6th of a mole. One mole is 6.022E23 atoms, but you only have 1/6th of that. I hope that thinking about it stepwise like this makes sense to you. It works the same for other atoms and molecules too. In a molecule, you would just add up the molar mass of all the component atoms. I hope this helps.
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