Using clay (or glazing compounds), make a doughnut. Without puncturing or tearing the doughnut, reshape it into a topologically equivalent figure, a cut with a handle.

MiniLab 2 Which of these compounds could the following "tack model" represent: magnesium chloride, potassium sulfide, calcium oxide, or aluminum bromide?

What do the following set of compounds/ions have in common?

$$\mathrm{O}_3, \mathrm{SO}_2, \mathrm{NO}_2^{-}$$

Predict whether the following compounds is water soluble or fat soluble.

stearic acid, CH$_{3}$(CH$_{2}$)$_{16}$COOH

Draw the condensed or line-angle structural formula, if cyclic, for each of the following naturally occurring compounds:

a. 2,5-dichlorophenol, a defense pheromone of a grasshopper

Predict the empirical formulas of the ionic compounds formed from the following pairs of elements. Name each compound.

$\mathrm{Li}$ and $\mathrm{N}$

(a) Use the relative bond lengths of the C-C and C-O bonds to predict which of the following two equilibria lies farther to the right. (That is, predict which of the two compounds contains more of the conformation with the axial methyl group.) (b) Which one of the following compounds contains the greater amount of gauche conformation for internal rotation about the bond shown? Explain.

Which of the following pairs of elements will not form ionic compounds? a. sulfur and oxygen b. sodium and calcium c. sodium and sulfur d. oxygen and chlorine

trans-Cyclodecene boils at 193°C, but cis-cyclodecene boils at 195.6 °C. Write stru ctural formulas for these two compounds.

Predict whether each of the following compounds is soluble or insoluble in hexane, C$_{6}$H$_{14}$.

trichloroethylene, C$_{2}$HCl$_{3}$

Assign oxidation states for all atoms in each of the following compounds. $\mathrm{Na}_{4} \mathrm{Fe}(\mathrm{OH})_{6}$

Three naturally occurring iron compounds are pyrite $(FeS_2)$, hematite $(Fe_2O_3)$, and siderite $(FeCO_3)$. Which contains the greatest percentage of iron?

Transform the given equation

$$\begin{gather*} t^2 U'' + 3t U' + 5 U = t^2 + 4 \end{gather*}$$

into a system of first order equations.

Use linearity and Table of the Laplace transforms to determine the Laplace transform of the function $f(t)=3+t+e^{-t} \sin 2 t$.