Is it possible for something with more mass to be lighter than something with less mass?

Yes, depending on the context.

If the more massive object is located in an environment that either provides an upward force or has less downward acceleration, then it may exert less force in the downward direction (weigh less) than an object with less mass.

Examples:

1. a 110 kg object weighed under water may show less weight than a 100 kg object weighed in air—particularly if it is much less dense.*

2. a man of mass 80 kg weighed on Earth's moon will definitely show less weight than a 100 kg man weighed on Earth.

* Actually, density has an effect on weight anytime the weighing is done in a medium other than a vacuum. (This is a potential source of error when trying to calibrate scales to very high accuracy.) When weighing is done in water, for example, an object of sufficiently low density will float, so show no weight at all.

it is a good conductor

explanation:

let that person have a turn to speak : )