13. Atoms of iron can have a valency of either 2 or 3.        What is the name given to compounds formed from iron atoms with a valency of 2?                  a) Ferry       b)Ferric     c) Ferrous

all of these substances turn litmus paper into red except….. a)HCl     b)HNO3       c)NaOH

all of these salts dissolve in water except …..                   a)sliver chloride.               b)sodium chloride.            c)sodium sulphate.

2) when a nonmetal gains or shares two electrons, it’s valency will be ….. a)monovalent        b)divalent c)trivalent

Ammonium chloride salt is formed on the combination of ….. a)a negative nonmetal ion with a positive atomic group.     b)a negative nonmetal ion with a negative nonmetal ion.      c)a positive metal ion with a negative atomic group

…….. are the most stable elements. a)metals b)nonmetals c)noble gases

all of the following are monovalent atomic groups except …….. group           a)nitrate.          b)hydroxide.                     c)phosphate.

1) when an acid dissolves in water, it produces …… ions.      a)(OH)+      b)H-        c)H+

on the combination of (Mg)+2 ion with (CO3)-2 group……..is formed.                                           a)an acid         b)a base     c) a salt

1) when an base dissolves in water, it produces …....… ions. a)(OH)+ b)H- c)H+

6) Nitrate and nitrite groups are different in the …. .....a)types of atoms.      b)number of atoms.        c)valency.

all of these substances turn litmus paper into blue except….. ...a)NaOH         b)KOH       c)HBr