Question

Calculate the number of moles of helium present in 52 g of helium.
A.) 0.050
B.) 13
C.) 1.0
D.) 1.5
E.) 2.0

Answer 1

Hint: To find the number of moles for any given substance, we just need to divide the given weight by the atomic/molecular weight of the substance. Now just try to figure out the final answer.

Complete step by step answer:

In the question, we are given 52 g mass of Helium.
We know that the molecular mass of helium gas is 4 u.
We know the formula for calculating moles,
$Moles\quad =\quad \dfrac { mass\quad of\quad substance }{ Molecular\quad mass\quad of\quad substance } $
Here the mass of substance = 52 g; the molecular mass of substance = 4 u.
So, $Moles\quad =\quad \dfrac { 52 }{ 4 }$ = 13 moles

Therefore, the correct answer to this question is option B.

Additional information:
Helium (He), chemical element, inert gas of Group 18 (noble gases) of the periodic table. The second lightest element (only hydrogen is lighter), helium is a colorless, odorless, and tasteless gas
Helium gas is used to inflate blimps, scientific balloons, and party balloons. It is used as an inert shield for arc welding, to pressurize the fuel tanks of liquid-fueled rockets and in supersonic wind tunnels.

Note: We should also know that one mole of any substance contains 6.022x${ 10 }^{ 23 }$ particles. Here, in this case, He has 13 moles that mean it has 13x6.022x${ 10 }^{ 23 }$ = 78.286x${ 10 }^{ 23 }$ particles.