For real world purposes, the density and temperature of the sun's core are such that ten pounds would probably be a pinhead size, which would very rapidly expand (with explosive force) to a volume of several hundred liters, while cooling as it expands to a temperature not far above room temperature.

It would not "nuke the entire continent" -- it's nearly pure hydrogen, and the heat content of ten pounds of hydrogen (even at several million degrees) isn't even equivalent to a small nuclear device. Initially, it would be hot enough that most of its radiation would be in X-ray, but the expansion (and cooling per Boyle's Law) would take milliseconds at most, leaving the gas too cool to radiate in visible light at all. For some portion of the expansion, the gas would radiate brilliantly in visible, IR, and UV light, but that radiative period would be a fraction of the expansion time.

The effect would be much like looking into a strobe flash -- dazzling, but not blinding. The explosion would be smaller in volume than a Fireball spell, and likely do less damage. It would certainly not penetrate a Wall of Force (though if the Wall isn't closed, the explosive shock wave would likely wrap around the ends/top and lead to temporary deafness, like a nearby grenade explosion). The hydrogen would surely ignite, but (mixing with air only at a spherical interface) wouldn't produce an explosion as such, just a very quickly abating puff of invisible flame.

In other words, the caster would be much better served using a perfectly ordinary Fireball spell for the same effect.

For real world purposes, the density and temperature of the sun's core are such that ten pounds would probably be a pinhead size, which would very rapidly expand (with explosive force) to a volume of several hundred liters, while cooling as it expands to a temperature not far above room temperature.

It would not "nuke the entire continent" -- it's almost entirely hydrogen and helium, and the heat content of ten pounds of that gas (even at several million degrees) isn't even equivalent to a small nuclear device. Initially, it would be hot enough that most of its radiation would be in X-ray, but the expansion (and cooling per Boyle's Law) would take milliseconds at most, leaving the gas too cool to radiate in visible light at all. For some portion of the expansion, the gas would radiate brilliantly in visible, IR, and UV light, but that radiative period would be a fraction of the expansion time.

The effect would be much like looking into a strobe flash -- dazzling, but not blinding. The explosion would be smaller in volume than a Fireball spell, and likely do less damage. It would certainly not penetrate a Wall of Force (though if the Wall isn't closed, the explosive shock wave would likely wrap around the ends/top and lead to temporary deafness, like a nearby grenade explosion). The hydrogen would surely ignite, but (mixing with air only at a spherical interface) wouldn't produce an explosion as such, just a very quickly abating puff of invisible flame.

In other words, the caster would be much better served using a perfectly ordinary Fireball spell for the same effect.