No, silica gel is a gritty sand like material used to absorb water and thus keep humidity down in sensitive devices.
Perhaps (considering your misspelling) you were thinking of silicone grease. Yes, silicone grease is a white colored sticky synthetic grease with good thermal conduction properties that is applied between a high wattage component and a heatsink. It is not as good a thermal conductor as metal, but is used primarily to prevent voids between the component and the heatsink which would cause hotspots.
If a truly good thermal conductor is needed between a component and the heatsink, silver filled epoxy would be the best material.
Yes
the worst conductors of heat are wood, plastic, rubber, and cloth.
Conductor. You're trying to move heat, not block it.
The estimated thermal conductivity of francium is 15 W/m.K.
Generally thicker walls slow down the transfer of heat, and if the material is a good thermal conductor that will increase the rate of transfer.
No, milk is not a good conductor.
After the published tables the silica aerogel is a very good thermal insulator. A vacuum, as in devoid of any matter.
Yes, that is what "good thermal conductor" means.
the worst conductors of heat are wood, plastic, rubber, and cloth.
A material that is a good thermal conductor would hold in a lot of heat. These thermal conductors would also transfer heat easily.
Conductor. You're trying to move heat, not block it.
Yes, being a metal, aluminum is a good thermal conductor.
A good thermal conductor is a piece of material that conducts heat fast. This means it accepts heat readily but it also looses heat at the same rate of change.
After the published tables the silica aerogel is a very good thermal insulator.
Heat flows easily in a good thermal conductor.
Yes. As with most metals, steel is a good conductor of heat.
With a thermal conductivity of 237 W/m.K aluminium is a good conductor of heat.
Silver is a good thermal conductor as it's a metallic element with many free electrons available for heat transfer.