What is the mass number of a fluorine atom with 8 neutrons?

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

As we move from left to right across the periodic table, what is the general trend? a) atomic radii increase. b) electronegavitiy decreases. c) nuclear shielding increases. d) metallic character decreases.

Which fossil fuel is mainly used for heating and cooking? a. electricity b. coal c. petroleum d. natural gas