Which term refers to a variable that is not allowed to change during an experiment

In a voltaic cell, electrons flow from the (positive/negative) to the (positive/negative) terminal.

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?

A0.580-kg rock is tied to the end of a string and is swung in a circle with a radius of 0.500 meters. the velocity of the rock is 4.50 m/s. what is the centripetal force acting on the rock? 15.5 n 5.22 n 69.8 n 23.5 n