$0.1 \text{ mole}$ of potassium permanganate was heated at $300^{\circ}C$. What is the weight (in $g$) of the residue? ($Mn = 55 \text{ u}$,$K = 39 \text{ u}$,$O = 16 \text{ u}$)

When a hydrated salt,$Na_2SO_4 \cdot nH_2O$,is heated,it loses $56\%$ of its weight and becomes anhydrous. What is the approximate value of $n$?

What is the stoichiometric ratio of the products in the reaction: $3K_2MnO_4 + 2H_2SO_4 \rightarrow 2KMnO_4 + 2K_2SO_4 + MnO_2 + 2H_2O$?

How many grams of zinc are required to produce $224 \ mL$ of hydrogen from dilute $H_2SO_4$ at $STP$?

$A$ $10 \ g$ effervescent tablet containing sodium bicarbonate $(NaHCO_3)$ and oxalic acid $(H_2C_2O_4)$ releases $0.25 \ L$ of $CO_2$ at $T = 298.15 \ K$ and $p = 1 \ bar$. If the molar volume of $CO_2$ is $25.0 \ L \ mol^{-1}$ under these conditions,what is the percentage by mass of sodium bicarbonate in each tablet? [Molar mass of $NaHCO_3 = 84 \ g \ mol^{-1}$,Molar mass of $H_2C_2O_4 = 90 \ g \ mol^{-1}$]

The normality of $1 \ M$ solution of $H_3PO_4$ will be.....$N$