Answer:
Solid helium requires a temperature of 1–1.5 K (about −272 °C or −457 °F) at about 25 bar (2.5 MPa) of pressure.
Thermal conductivity: 0.1513 W/(m⋅K)
Molar heat capacity: 20.78 J/(mol·K)
Boiling point: 4.222 K (−268.928 °C, −452....
Critical point: 5.1953 K, 0.22746 MPa
