According to the periodic table, carbon's molar mass is 12.011 grams per mole (that's the small number under the element). So, just multiply like this to get the answer:

So, there are approximately 0.208 grams in 2.5 moles of carbon.
Answer :
(a) The energy of blue light (in eV) is 2.77 eV
(b) The wavelength of blue light is 
Explanation:
The relation between the energy and frequency is:

where,
h = Plank's constant = 
Given :
Frequency = 
Conversion used :

So,


Also,

So,


The energy of blue light (in eV) is 2.77 eV
The relation between frequency and wavelength is shown below as:

Where,
c = the speed of light = 
Frequency = 
So, Wavelength is:


Conversion used : 
The wavelength of blue light is 
Answer:
1.56 mol H₂
Explanation:
Mg₃(Si₂O₅)₂(OH)₂
<em>There are 4 Si moles per Mg₃(Si₂O₅)₂(OH)₂ mol</em>. With that in mind we can <u>calculate how many Mg₃(Si₂O₅)₂(OH)₂ moles are there in the sample</u>, using the <em>given number of silicon moles</em>:
- 3.120 mol Si *
= 0.78 mol Mg₃(Si₂O₅)₂(OH)₂
Then we can <u>convert Mg₃(Si₂O₅)₂(OH)₂ moles into hydrogen moles</u>, keeping in mind that <em>there are 2 hydrogen moles per Mg₃(Si₂O₅)₂(OH)₂ mol</em>:
- 0.78 mol Mg₃(Si₂O₅)₂(OH)₂ * 2 = 1.56 mol H₂
Hey There!
At neutralisation moles of H⁺ from HCl = moles of OH⁻ from Ca(OH)2 so :
0.204 * 42.8 / 1000 => 0.0087312 moles
Moles of Ca(OH)2 :
2 HCl + Ca(OH)2 = CaCl2 + 2 H2O
0.0087312 / 2 => 0.0043656 moles ( since each Ca(OH)2 ives 2 OH⁻ ions )
Therefore:
Molar mass Ca(OH)2 = 74.1 g/mol
mass = moles of Ca(OH)2 * molar mass
mass = 0.0043656 * 74.1
mass = 0.32 g of Ca(OH)2
Hope that helps!