Low melting points and boiling points. ...Low enthalpies of fusion and vaporization These properties are usually one or two orders of magnitude smaller than they are for ionic compounds.Soft or brittle solid forms. ...Poor electrical and thermal conductivity.
<u>Answer:</u> The force that must be applied is 15 N.
<u>Explanation:</u>
Force exerted on the object is defined as the product of mass of the object and the acceleration of the object.
Mathematically,

where,
F = force exerted = ?
m = mass of the object = 3 kg
a = acceleration of the object = 
Putting values in above equation, we get:

Hence, the force that must be applied is 15 N.