What must occur for air masses to form fronts

As air becomes more dense, (select all that apply) o. air weighs less o. gas molecules are closer together o. air is colder o. air weighs more o. gas molecules are further apart o. air is hotter

Which statement is true about this reaction? 14n+1h 15o it is a practical source of energy on earth. it occurs only outside the solar system. its product is heavier than each of its reactants. it shows the critical mass of an element.

How does concentration affect reaction rate