Antoine lavoisier is often referred to as the "father of modern chemistry". this is partly because of his discovery of the role of oxygen in combustion reactions but also his discovery that a) neutrons have no charge. b) the atom contains a positively-charged nucleus. c) the masses of the reactants and products are equal. d) atoms of the same element can have different masses.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

Earth's axis of rotation is tilted at an angle of 23.5 degrees. what is one change you would see on earth if its axis was not tilted?

Identify arrows pointing to bonding electrons. done h-0-0-h ) intro