When a substance goes directly from a solid state to a gas state as dry ice

Sublimation

Explanation:

Sublimation refers to the process by which the change of matter takes place directly from solid to liquid state. The matter from the solid-state directly changes into the gaseous state without changing into the liquid state. More energy is required in this process. This is an endothermic reaction. Dry ice is the solid carbon dioxide sublimes in the air.

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

sorry idk the answer well to you i have a explaination

explanation: a formula which shows the arrangement of atoms in the molecule of a compound