please show work so I can learn how to do it. Thank you :)

81. Write a formula for each acid. (a) Nitrous acid (b) Hydrofluoric acid (c) Chloric acid

85. Arrange the compounds in order of decreasing formula mass. Ag2O, PtO2, Al(NO3)3, PBr3

89. How many chlorine atoms are in each set? (a) three carbon tetrachloride molecules (b) two calcium chloride formula units (c) four phosphorus trichloride molecules (d) seven sodium chloride formula units

93. Complete the table: Formula Type of Compound (Ionic, Molecular, Acid) N2H4 molecular ________ ________ H2CrO4(aq) ________ ________ ________ Name ________ potassium chloride ________ cobalt(III) cyanide

97. For each compound, list the correct formula and calculate the formula mass. (a) Manganese(IV) oxide (b) Silicon tetrachloride (c) Potassium bicarbonate (d) Boron tribromide

101. A compound contains only sulfur and fluorine and has a formula mass of 146.1 amu. What is its molecular formula?