Help please Students were asked to compare Sodium, Magnesium, Potassium, and Calcium,
Which statement is true
A. Na and Mg have 3 valence electrons
B. Na and K are highly reactive C. K and Ca are in the same group
D. Mg and Ca have two energy levels.

Consider the elements bromine and chlorine; which elements has a larger ionic radius ?

Fill in the coefficients that will balance the following reaction: a0cr2(so4)3 + a1agno3

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.