Which one of these chemical equations is already balanced? (Hint: count how many of each kind of atom on each side). You can use scratch paper.
Ca + 202 - 2Cao,
2Ca + 02 - 2Cao
Ca + 0, - Cao
Ca + 20
2Ca + O2

Check the correct box to describe the periodic trends in electronegativity. electronegativity across a period: decreases. increases. electronegativity down a group: decreases. increases.

The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.

All of the following are homogeneous mixtures except a) sugar dissolved in water. b) orange juice. c) coffee with cream. d) household vinegar. e) apple juice