Which of the the following statements is true? 1. In the periodic table, the ectronegativity of an atom generally decreases from right to left, and increases from top to bottom.
2. In the periodic table, the ectronegativity of an atom generally decreases from right to left, and decreases from top to bottom.

Answer ozone (o3) is made of three atoms of oxygen, it is a molecule;

Caso4(s) < > ca+2 + so4^-2 ksp = [ca+2][so4^-2] = 2.4 x 10^-5 = [0.20][so4^-2] [so4^-2] =1.2 x 10^-4 ag2so4(s) ,> 2ag+ + so4^-2 ksp = [ag+]^2[so4^-2] = 1.5 x 10^-5 = (0.30)^2[so4^-2] [so4^-2] = 1.5 x 10^-5/0.09 = 1.7 x 10^-4 caso4 would precipitate first since it requires less so4^- to form a saturated solution.  i believe this is right, i hope it !  

The correctly balanced equation is  2h2 +o2 =2 h2o