The sound of an explosion in space

It has been said that in space, no one can hear you scream. Why? Because sound travels through particles and particles in space are few and far between. So sound doesn't usually get very far in space.

But with enough energy peculiar things happen. A black hole has been observed to sing a B flat 57 octaves below middle C in the Perseus cluster of galaxies located 250 million light years from Earth.

Would this be the only form of sound traveling in space? Doubtful... My own hypothesis is that explosions would generate a sound even in a perfect vacuum with no particles. I doubt anyone has ever done it. But I believe the particles of the explosion itself would carry kinetic energy until colliding with something... anything that could carry sound... such as the hull of a space craft. Now I just need someone to go up there and test it.

Another question: what is the speed of sound in space? If a tree exploded in outer space and no one was there? Would that make a sound?

Clock angle

It is 6:30 on a normal clock with a face. What is the angle between the hour hand and the minute hand?

What would the angle be at 6:35.27?