A certain element $X$ forms a compound with oxygen in which there are two atoms of $X$ for every three atoms of $\mathrm{O}$. In this compound, $1.125 \mathrm{~g}$ of $X$ are combined with $1.000$ $\mathrm{g}$ of oxygen. Use the average atomic mass of oxygen to calculate the average atomic mass of $X$. Use your calculated atomic mass to identify the element $X$.

Sodium carbonate $\left(\mathrm{Na}_2 \mathrm{CO}_3\right)$ placed in water forms a basic solution. Carbonic acid $\left(\mathrm{H}_2 \mathrm{CO}_3\right)$ in water forms an acidic solution. Use equations to explain these results:

Given item below contains an error in sentence structure, subject-verb agreement, pronoun, antecedent agreement, placement of a modifier, verb forms, pronoun forms, or formal, standard English Revise given sentence to correct any errors.
Each of the gymnasts performed their routine for the coach.

Multiple choice is the format used for most national certification examinations. Choose the correct answer to the statement or question. (LO 3.2, 3.3, 3.4, 3.7, 3.8)

What forms the gliding surface where two bones meet to form a joint? a. cartilage b. blood vessels c. collagen d. ligaments e. lymph

Determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement. Credit reports contain bankruptcy information. ____

Suppose you want to simplify the following expression: $4 x^{\frac{2}{2}}+3 \sqrt{x^3}$.

• How can you write the radical expression using a rational exponent?

• Can you add the resulting terms?

-What is the result in simplest form?

• Can you write the result in two equivalent forms?

Suspension bridges can span distances far longer than any other kind of bridge. The roadway of a suspension bridge is suspended from huge cables. When a flexible cable is suspended between two points, it forms a catenary curve. Use a graphing calculator to graph the catenary $y=\frac{e^{x}+e^{-x}}{2}$.

Net income for the year for Carrie, Inc. was $750,000, but the statement of cash flows reports that net cash provided by operating activities was$860,000. What might account for the difference?

Suggest why $\mathrm{Be}^{2+}$ forms the tetrahedral ion $\left[\mathrm{Be}\left(\mathrm{OH}_2\right)_4\right]^{2+}$, while $\mathrm{Mg}^{2+}$ forms octahedral $\left[\mathrm{Mg}\left(\mathrm{OH}_2\right)_6\right]^{2+}$.

The following table presents the number of reports of graffiti in each of New York’s five boroughs over a one-year period. These reports were classified as being open, closed, or pending.

$$\begin{array}{lrrrr} \hline & \text{Open} & \text{Closed} & \text{Pending} & \\ \text{Borough} & \text{Reports} & \text{Reports} & \text{Reports} & \text{Total}\\ \hline \text{Bronx} & 1,121 & 1,622 & 80 & 2,823\\ \text{Brooklyn} & 1,170 & 2,706 & 48 & 3,924\\ \text{Manhattan} & 744 & 3,380 & 25 & 4,149\\ \text{Queens} & 1,353 & 2,043 & 25 & 3,421\\ \text{Staten Island} & 83 & 118 & 0 & 201\\ \hline \text{Total} & 4,471 & 9,869 & 178 & 14,518\\ \end{array}$$

A graffiti report is selected at random. Compute the following probabilities.

$\textbf{a.}\hspace{10pt}$ The report is open and comes from Brooklyn.

$\textbf{b.}\hspace{10pt}$ The report is closed or comes from Queens.

$\textbf{c.}\hspace{10pt}$ The report comes from Manhattan.

$\textbf{d.}\hspace{10pt}$ The report does not come from Manhattan.

$\textbf{e.}\hspace{10pt}$ The report is pending.

$\textbf{f.}\hspace{10pt}$ The report is from the Bronx or Staten Island.

Find out three recent news reports that quote percentages. In each case, describe the use of the percentage (as a fraction, to describe change, or for comparison) and explain its context.

State the claim mathematically. Write the null and alternative hypotheses. Identify which is the claim.

A research organization reports that 33% of the residents in Ann Arbor, Michigan are college students.

Consider the transition between two forms of solid tin, $\operatorname{Sn}(s$, gray $) \rightarrow \operatorname{Sn}(s$, white $)$. The two phases are in equilibrium at $1 \mathrm{bar}$ and $18^{\circ} \mathrm{C}$. The densities for gray and white tin are $5750$ and $7280 \mathrm{~kg} \mathrm{~m}^{-3}$, respectively, and the molar entropies for gray and white tin are $44.14$ and $51.18 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$, respectively. Calculate the temperature at which the two phases are in equilibrium at $350 . \mathrm{bar}$.

Hydrolysis of the compound $B_5H_9$ forms boric acid , $H_3BO_3.$ Fusion of boric acid with sodium oxide forms a borate salt, $Na_2B_4O_7$. Without writing complete equations, find the mass (in grams) of $B_5H_9$ requ ired to form 151 g of the borate salt by this reaction sequence.