40 POINTS PLEASE HELP!!

An object's buoyant force and weight mean the same thing.a. trueb. false

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?