A painter needs to buy a new pulley system. Both systems have an input work of 100 J, but the old system model has an output work of 60 J and the new system model has an output work of 75 J. Which system is more efficient?

Arock can be broken down into different kinds of substances by physical processes. no chemical reactions are needed to separate different parts of a rock into pure substances. this is because a rock is a(n)

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Which of the following electromagnetic waves can create ions?