Who was a leading authority on continental drift in the early 1900s? OPTIONS:
- Alfred Wegener
- Albert Einstein
- Charles Richter
- Charles Darwin
A: Alfred Wegener

In a mixture, a magnet is used to separate some particles from sand. The dark particles are most likely made of which element? OPTIONS:
- sodium
- iron
- sulfur
- copper
A: iron

An Italian scientist named Alessandro Volta invented the Voltaic pile in 1800. It was able to produce a steady electrical current. Based on this description, what is the modern equivalent of the Voltaic pile? OPTIONS:
- a wire
- a battery
- a resistor
- a light bulb
A: a battery

Which is the best example of a pure substance? OPTIONS:
- peanuts
- milk
- gold
- air
A:
gold