Of course, this is a trick question, akin to asking about a tonne of feathers versus a one tonne elephant. We know that both weigh the same – one tonne.
In terms of precious metal however, the trick is in the metal density. Gold is a much denser element and therefore, in terms of volume, gold is much heavier! Without delving into “Specific Gravities”, or “Atomic Numbers”, or even counting protons… the above can be plainly seen by referring back to our feathers and elephants!
Picture an elephant. Now, picture enough feathers to make up the same amount of space as that elephant. It is easy to imagine that, though the feathers take up the same volume, they will not weigh as much as the heavily packed elephant. It is the same for gold and silver and is the reason why a one kilogram bar of silver (i.e. the feathers!) is physically larger than a one kilogram bar of gold (the elephant!) even though they both weight exactly the same amount – one kilo!
Now, just for fun… consider a 5 kilo bar of gold. Armed with the above information, imagine how AMAZING it must be to hold one in your hands!