Hydrogen boils at 20k. what is the boiling point of hydrogen on the celsius scale

Celsius scale is related to kelvin scale by the following equation,

⁰C = K-273

°C = K-273  

So as here temperature is given in kelvin, so it can be converted into celsius as follows:

So 20 K = 20K-273 °C  

= -253 °C .

So, the 20 K temperature equals to -253 °C.

So , -253 °C is equals to  20 K or 20 K temperature equals to -253 °C.

b. atoms in metallic solids are not arranged in a regular pattern

explanation: