If Earth was the size of an orange, what consistency would it be? I understand that the Earth is composed of a thin crust "floating" over a semi-solid layer of mantle.
I was wondering how it would feel at a human scale, say the size of an orange in your hand. Could you somewhat squeeze it or would it rather be  totally solid?
 A: At first you'd burn your hand, then it would feel like a normal rock.
An orange sized Earth would cool very rapidly.
If an object gets twice as big, its volume increases by $2^3$, but its surface increases only by $2^2$. You can only lose heat at the surface but you 'hold' all your heat in your interior. Simply said, the bigger something is, the harder it is to lose heat. That's also why small mammals eat so much - mice eat their own body weight in 6 days! - they lose heat to their environment very easily.
If you consider the alternative - increasing your hand to the scale of the Earth - it won't end well for you. 
A: The diameter of the earth is about 12,000 km. The highest point on earth is mount Everest at about 8 km. This is less than 0.1 % of the earth diameter. Scaling down the earth to the size of an orange, say about 12 cm diameter, would make mount Everest have a relative size of about 80 micron - hardly visible under a magnifying lens. So the earth would appear as a very smooth surface. The oceans are perhaps 12 km at the deepest point, thus the oceans would appear as a very thin water film on the surface - similar to a wet surface on a marble.  At such a scale, the mantle would be fully solid. Even if it was still a semi solid at this scale, it would be like trying to crush a rock. You could do it with a hammer :) 
