The element copper cu has two naturally occurring isotopes. 69% of all coopers consist of atom with 34 neutrons, 31% of all samples with 36 neutrons. calculate the average atomic weight of cooper atoms

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

If we compare and contrast electromagnetic waves with sound waves, all but one statement is true. that is a) sound waves require a medium to travel while electromagnetic waves do not. b) electromagnetic waves can travel through the vacuum of space while sound waves cannot. c) electromagnetic waves must have a medium in which to travel, but sound waves can travel anywhere. eliminate d) sound waves must bounce off of matter in order to travel while electromagnetic waves do not require matter to be present.

Which of the following is not an assumption that scientists must make about the natural world? a. regularity b. causality c. predictability d. plausibility