The molecules which evaporate into the gas phase are the ones traveling with velocity.

Explanation:

In gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they tend to move rapidly from one place to another leading to more number of collisions.  

Therefore, when number of collisions increases then force applied by the molecules on each other also increases.

As a result, velocity of the particles increases.

Therefore, we can conclude that the molecules which evaporate into the gas phase are the ones traveling with high velocity.

the law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. because atoms are only rearranged in a chemical reaction, there must be the same number of sodium atoms and chlorine atoms in both the reactants and products