What's the force that causes lava to erupt?

Acharreadas is a popular mexican thing where people display varying skills of horsemanship much like what events in the united states?

After railroads, the next revolution of transportation came with the development of (a) automobile (b) telegraph (c) steam engine

Renaldo and nasreen build an electromagnet by wrapping a wire around a nail and connecting the wire to both terminals of a battery. when they test the electromagnet, it can pick up 6 paper clips. their teacher wants all groups to pick up at least 10 paper clips. what could renaldo and nasreen do to increase the number of paper clips their electromagnet picks up?