223 – Referring to the figure below, a solution with the characteristics of point A is prepared from four compounds. In each of the four separate containers, 100 g of water is prepared at $70^\circ$C and then the solution temperature is decreased to $20^\circ$C. In which container is the amount of precipitate formed the least, and what is the approximate weight of the precipitate formed in grams?
[Figure: Solubility vs. temperature graph showing curves for various compounds, with point A marked]

1. Potassium chloride, 28
2. Sodium nitrate, zero
3. Potassium dichromate, 48
4. Lead(II) nitrate, 5

224 – Referring to the figure below, for the hypothetical reaction $\text{A} \rightarrow \text{B}$ in a 4-liter container, the average reaction rate from time $t_2$ to $t_4$ is how many $\text{mol·L}^{-1}\text{·min}^{-1}$, and how many times is it equal to the average rate from time $t_2$ to $t_4$? (Assume each ball represents $0.05$ mol of each substance.)
[Figure: Four containers at $t_1=0$ min, $t_2=20$ min, $t_3=40$ min, $t_4=60$ min showing black dots (A) and white dots (B)]

(1) $1/5\ ,\ 7/5\times10^{-3}$	(2) $1/5\ ,\ 1/875\times10^{-3}$
(3) $3\ ,\ 1/875\times10^{-3}$	(4) $3\ ,\ 7/5\times10^{-3}$

225 – Given the following mechanism, which is the correct overall reaction equation?

1. $2\text{NO}(\text{g}) \rightarrow \text{N}_2\text{O}_2(\text{g})$
2. $2\text{H}_2(\text{g}) \rightarrow 4\text{H}(\text{g})$
3. $\text{N}_2\text{O}_2(\text{g}) + \text{H}(\text{g}) \rightarrow \text{N}_2\text{O}(\text{g}) + \text{HO}(\text{g})$
4. $2\text{HO}(\text{g}) + 2\text{H}(\text{g}) \rightarrow 2\text{H}_2\text{O}(\text{g})$
5. $\text{H}(\text{g}) + \text{N}_2\text{O}(\text{g}) \rightarrow \text{HO}(\text{g}) + \text{N}_2$

(1) $2\text{OH}(\text{g}) + 2\text{H}(\text{g}) \xrightarrow{\text{N}_2\text{O}_2(\text{g})} 2\text{H}_2\text{O}(\text{g})$	(2) $\text{N}_2\text{O}_2(\text{g}) + 2\text{H}(\text{g}) \rightarrow \text{N}_2\text{O}(\text{g}) + \text{H}_2\text{O}(\text{g})$
(3) $2\text{NO}(\text{g}) + \text{H}_2(\text{g}) \rightarrow \text{N}_2\text{O}(\text{g}) + \text{H}_2\text{O}(\text{g})$	(4) $2\text{NO}(\text{g}) + 2\text{H}_2(\text{g}) \rightarrow \text{N}_2(\text{g}) + 2\text{H}_2\text{O}(\text{g})$

226 – Which option is incorrect?

1. Crystals have a high ability to adsorb gaseous substances present in the air.
2. In the decomposition of potassium chlorate by heat, manganese dioxide plays the role of a heterogeneous catalyst.
3. In the catalytic hydrogenation of alkenes, the size of the catalyst particles has no effect on the reaction rate.
4. In the decomposition of $\text{N}_2\text{O}$ on a $\text{N}_2\text{O}$ surface, doubling the concentration of $\text{N}_2\text{O}$ keeps the reaction rate constant.

227 – For the reaction $\text{A}(\text{g}) + 2\text{B}(\text{g}) \rightarrow \text{AB}_2(\text{g})$, the concentration of substance A decreases by half every hour. If the initial concentration of substance A is $1\ \text{mol·L}^{-1}$, how many hours are needed for $93.75\%$ of the $\text{AB}_2$ molecules to decompose?

(1) 4

(2) 5

(3) 8

(4) 10

\begin{flushright} Calculation Space \end{flushright}
www.riazisara.ir
%% Page 37
Download Exam Questions from Riazisara.ir
\begin{flushright} Chemistry 120-C Page 20 \end{flushright}

228. In an experiment, $0.5$ mol $\mathrm{N_2(g)}$, $0.5$ mol $\mathrm{O_2(g)}$, and $0.25$ mol $\mathrm{NO(g)}$ are introduced into a $250\,\mathrm{mL}$ flask and allowed to reach equilibrium for the reaction: $$\mathrm{N_2(g) + O_2(g) \rightleftharpoons 2NO(g)},\quad K = 4\times10^{-4}$$ The concentration of gas $\mathrm{NO}$ at equilibrium is approximately how many $\mathrm{mol\cdot L^{-1}}$?
(1) $1/1$ (2) $1/05$ (3) $0/05$ (4) $0/1$

229. Based on the reaction: $\mathrm{A(g) + 3B(g) \rightleftharpoons 2C(g)}$, $K = 6.22\,\mathrm{L^2\cdot mol^{-2}}$, if $0.1$, $0.2$, and $0.3$ mol of substances $\mathrm{A(g)}$, $\mathrm{B(g)}$, and $\mathrm{C(g)}$ respectively are introduced into a one-liter flask, which graph correctly shows the change in their concentrations?
[Figure: Four graphs (1)--(4) showing molarity vs. time plots for substances A, B, and C approaching equilibrium]

230. Esters, in water undergo a reaction and are converted to \ldots\ldots\ldots\ and \ldots\ldots\ldots\ (carboxylic acids).
(1) reversible -- very slow -- alcohols (2) reversible -- fast -- glycerin
(3) irreversible -- very slow -- alcohols (4) irreversible -- fast -- glycerin

231. To the $\mathrm{pH} = 2$ solution of $0.01\,\mathrm{M}$ hydrochloric acid, how many grams of potassium hydroxide ($M = 56\,\mathrm{g\cdot mol^{-1}}$) must be added to approximately double the $\mathrm{pH}$?
(1) $0/5$ (2) $0/55$ (3) $1/00$ (4) $1/11$

232. Approximately how many grams of the weak base $\mathrm{BOH(s)}$ ($M = 80\,\mathrm{g\cdot mol^{-1}}$) with $2\%$ degree of dissociation must be added to $250\,\mathrm{mL}$ of water to obtain a solution with $\mathrm{pH} = 11$?
(1) $1$ (2) $2$ (3) $4$ (4) $8$

233. Which statement about the preparation of sodium metal in the Downs cell is incorrect?
(1) Parts C and B of this cell are made of graphite and iron, respectively.
(2) For every mole of sodium metal produced, half a mole of chlorine gas is formed.
(3) The molten sodium obtained collects in vessel A inside the cell.
(4) To lower the melting point of sodium chloride, calcium chloride is added to it.
[Figure: Diagram of a Downs cell with parts labeled A, B, C]

234. If $E^\circ$ of the reaction $\mathrm{A(s) + B^{2+}(aq) \to B^{2+}(aq) + A(s)}$ is negative, and $E^\circ$ of the reaction $\mathrm{B(s) + D^{2+}(aq) \to B^{2+}(aq) + D(s)}$ is positive, which statement is always correct?
(1) The reducing power of these metals is: $\mathrm{D > A > B}$.
(2) The oxidizing power of the three metal cations is: $\mathrm{B^{2+} > D^{2+} > A^{2+}}$.
(3) The reaction $\mathrm{A(s) + D^{2+}(aq) \to A^{2+}(aq) + D(s)}$ is spontaneous under standard conditions.
(4) If the standard reduction potential of electrode D is $+0.33$ V, metal A reacts with hydrochloric acid solution.

235. In a galvanic cell, if instead of the standard zinc electrode, a mercury electrode is used, what change will occur? (The standard electrode potentials of mercury, zinc, and iron are $-0.76$, $-0.85+$, and $-0.44-$ volts, respectively.)
(1) $E^\circ$ of the cell decreases by $1.29$ volts. (2) The electrode of zinc is replaced by mercury.
(3) The amount of $\mathrm{Zn^{2+}(aq)}$ in the solution decreases. (4) The direction of electron current in the external circuit reverses.

Calculation Space
www.riazisara.ir

1) When it does a good deed twice! 2) When it falls into a pit! 3) When it falls into a hunter's trap! 4) When it sees the result of its mistake!

2) God gave teeth to the elephant so that it becomes a spectacle for hunters!

3) The elephant sees things precisely and can take them even if they are small!

4) The elephant does not search much for its food, so it eats plants and tree leaves!
\rule{\textwidth}{0.4pt}
Identify the Error in Formation (38 and 39)

13 amu. The difference between the lightest and heaviest molecular masses of carbon tetrachloride is how many amu?
(1) $6$ (2) $7$ (3) $8$ (4) $9$

23. Which of the following verses best matches the meaning of the given lines? Choose:

``I pray whenever the wind has told the cypress grove / my prayer follows me — the prayer of Al-Haram''

Theme: following/``wave of steps''

p{0.45\textwidth}} (1) If a bird's tongue is a rosary	what a rosary that speechless ox brings
(2) Not the nightingale's flower is a rosary	that every thorn is a rosary tongue
(3) A person is a anchor of inanimate things	and the master is in the worship of the master
(4) All of them recite his rosary	the sand in the desert and the stone of the hillside

24. Which of the following meanings of ``face-to-face'' is not correct?

(1) wherever a fish leapt from the water = (infinite longing of the mystic)
(2) one who is unaware of this is unaware = (unaware of love)
(3) the secret is not far from my lament = (unity of the outward and inward)
(4) no companion who would help by fleeing = (solidarity and companionship of the afflicted)

25. Verse: ``The secret of the heart's city'' ``Look, so that in the city of the falcon'' has no equivalent meaning with which verse?

p{0.45\textwidth}} (1) There is a secret in this veil, recognize it	do you know what reality is behind what veil of metaphor?
(2) And from the world your secret fell	burned, the secret is not to be kept as a sound
(3) Love will bring the word out	\={a}ine was like
(4) At the crossroads that the morning breeze plays	the caravan hid the musk, unable to conceal

%% Page 7 Arabic Language 111-C Page 6

$\blacksquare$ $\blacksquare$ Identify the most correct and precise answer for the translation, definition, or concept (26 -- 33)

26- ``من قُتِل مظلوماً، فقد جعلنا لوليّه سلطاناً '':

1. Whoever is killed unjustly, we give his guardian authority over his blood!
2. Whoever is killed unjustly, we place his guardian in the position of power, for the sake of blood!
3. If someone is killed unjustly, we grant his guardian sovereignty!
4. Someone who is oppressed by injustice, but we have made his guardian powerful!

27- ``الفُرص الذَّهبيّة تحصل لجميع الناس، و لكنّ النّاجحين هم الّذين يقتنصونها! '':

1. Golden opportunities exist for all people, but only the successful are those who seize them and make use of them!
2. Golden opportunities arise for all people, but the successful are those same people who seize them!
3. Golden opportunities are attainable for all people, but only the victorious individuals seize them!
4. For all people, golden opportunities come within reach, but only the successful individuals are able to seize them!

28- ``كان آباؤنا يؤكّدون دائماً أنّ طريق الوصول إلى العُلى هو الإحسان في حقّ النّاس! '':

1. Our fathers always emphasized that the way to reach greatness is doing good to people!
2. Our ancestors emphasized that the way to attain greatness is doing good, being kind to people!
3. Our fathers always emphasized that the way to reach greatness, doing good in people's right is!
4. Our ancestors always recommend that the way to reach greatness, doing good to people is!

29- ``كانت أشعّة القمر الفضيّة المتكوّنة من سبعة ألوان تخلب قلوبنا، عندما كنّا نمشي بهدوء على تلال الرّمل! '':

1. The silver moonbeams composed of seven colors had captivated us, when we walked calmly on the sandy hills!
2. The silver moonbeams with its seven colors captivated us, when we walked calmly on the sandy hills!
3. When we walked calmly on the sandy hills, the silver light of the moon composed of seven colors captivated our hearts!
4. When we stepped calmly on the sandy hills, the silver moonlight that had seven colors, captivated our hearts!