The arrangement of elements in the Modern periodic table is based on their A) increasing atomic mass in the period
B) increasing atomic number in the horizontal rows
C) increasing atomic number in the vertical columns
D) increasing atomic mass in the group

Dumbledore decides to gives a surprise demonstration. he starts with a hydrate of na2co3 which has a mass of 4.31 g before heating. after he heats it he finds the mass of the anhydrous compound is found to be 3.22 g. he asks everyone in class to determine the integer x in the hydrate: na2co3·xh2o; you should do this also. round your answer to the nearest integ