Potassium chlorate KClO3 decomposes when heated to produce potassium chloride, KCI and oxygen gas If 2.50 grams of KCIO3 were heated in a test tube, how many grams of oxygen has of (O2) should be given off

Please should The before , Change and after please I need to understand this

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

its first and third is your answer i did the qustion the fourth isnt right

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.