If a mineral breaks into cubes when struck with a rock hsmmer, which property is being measured? a.) hardness b.) cleavage c.) color d.) streak

hardness is NOT the right ans cuz' it says "breaks into cubes when struck with a rock hammer"

cleavage is a property that describes HOW a mineral will break up in what form, e.g. parallel sheets or cubes. so the ans is b.) cleavage

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach