Answer: The empirical formula for the given compound is 
Explanation : Given,
Percentage of C = 38.8 %
Percentage of H = 16.2 %
Percentage of N = 45.1 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of C = 38.8 g
Mass of H = 16.2 g
Mass of N = 45.4 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.
Moles of Carbon =
Moles of Hydrogen = 
Moles of Nitrogen = 
Step 2: Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 3.23 moles.
For Carbon = 
For Hydrogen = 
For Oxygen = 
Step 3: Taking the mole ratio as their subscripts.
The ratio of C : H : N = 1 : 5 : 1
Hence, the empirical formula for the given compound is 
Answer:
That would be helium, with a melting point of 0.95 K (-272.20 °C)—although this happens only under considerable pressure (~25 atmospheres). At ordinary pressure, helium would remain liquid even if it could be chilled to absolute zero.
Hi~~
H2O, commonly known as water, is definitely a compound.
David's conclusion is wrong because the hydrogen gas combined with oxygen from the air to form dihydrogen monoxide, also known as water.
The Formula to find the number of moles is:
Number of Moles = Mass/ Molar Mass
Which means that Mass = Number of Moles * Molar Mass
We know that Number of Moles of Sodium Na =

moles
If you check the Periodic Table, Molar Mass of Sodium Na = 23g/mol
So, Mass =

=
So, the mass in grams of

mol of Sodium is

Hope this Helps :)