From the conversion of units:
1 cm^3 is equivalent to 1 mL
1 L is equivalent to 1000 mL
therefore,
to convert from liter to cm^3, we simply multiply by 1000.
Note that the multiplication will be done in the denominator.
Based on this:
density = (0.625 g/l) x (1g/1000 cm^3) = <span> 0.000625 g/cm^3
= 6.25 x 10^-4 g/cm^3</span>
The mass of He gas = 21.428 g
<h3>Further explanation</h3>
Given
120 liters of He gas
Required
the mass in grams
Solution
Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.
Mol for 120 L :

Mass of He gas(MW=4 g/mol) :

Answer: A chemical reaction that stores energy is called an endothermic reaction. More energy might be released as products form than the energy needed to break the reactants apart.
Explanation:
Answer:
Molar mass = 0.09 × 10⁴ g/mol
Explanation:
Given data:
Mass = 0.582 g
Volume = 21.3 mL
Temperature = 100°C
Pressure = 754 mmHg
Molar mass = ?
Solution:
(21.3 /1000 = 0.0213 L)
(100+273= 373 K)
(754/760 = 0.99 atm)
PV = nRT
n = PV/RT
n = 0.99 atm × 0.0213 L / 0.0821 atm. L. mol⁻¹. k⁻¹ × 373 K
n =0.02 mol/ 30.6
n = 6.5 × 10⁻⁴ mol
Molar mass = Mass/ number of moles
Molar mass = 0.582 g / 6.5 × 10⁻⁴ mol
Molar mass = 0.09 × 10⁴ g/mol