218 -- If the following reaction takes place inside a cylinder with a movable piston, how many of the following statements about it are correct?
$$\mathrm{N_2H_4(g) + ClF_3(g) \rightarrow HF(g) + N_2(g) + Cl_2(g)}, \quad \Delta H < 0$$
(The equation is balanced.)

• $\Delta E$ equals $q + w$.
• $\Delta H$ equals $\Delta E - w$.
• The signs of $\Delta S$ and $\Delta G$ are negative.
• The system does work on the surroundings, and $w$ is positive.
• The sum of the stoichiometric coefficients of the substances in the balanced equation equals 24.

(1) 2 (2) 3 (3) 4 (4) 5

219 -- Which statement is correct?

1. $\Delta H^\circ$ of fusion of every substance is greater than its $\Delta H^\circ$ of vaporization.
2. $\Delta H^\circ$ of fusion and vaporization of water are greater than those of benzene.
3. Intermolecular forces play an important role in determining $\Delta H^\circ$ of fusion and vaporization.
4. The difference between $\Delta H^\circ$ of fusion and $\Delta H^\circ$ of vaporization of ice, compared to many liquids and gases, is smaller.

220 -- Considering the following reaction, how many grams of $\mathrm{I_2}$ are needed to form $0.2$ mol of $\mathrm{NO_2}$ gas and nitric acid, and how many liters of $\mathrm{HNO_3}$ solution at $5000\ \mathrm{ppm}$ are consumed? (Choose the options that fill in the blanks from left to right.)
$$(\mathrm{H = 1,\ N = 14,\ O = 16,\ I = 127\ :\ g.mol^{-1}})$$
$$\mathrm{I_2(s) + HNO_3(aq) \rightarrow HIO_3(aq) + NO_2(g) + H_2O(l)}$$
(The equation is balanced.)
(1) $2.25$,\ $5.08$ (2) $2.52$,\ $5.08$ (3) $2.25$,\ $2.54$ (4) $2.52$,\ $2.54$

221 -- How many of the following statements are correct?

• Dissolution of gases in water is exothermic.
• Solutions of some organic substances in water have electrical conductivity.
• Increasing pressure and temperature reverses the dissolution of gases in water.
• Decreasing temperature increases the solubility of lithium sulfates and potassium nitrates in water.

(1) 1 (2) 2 (3) 3 (4) 4

222 -- If $4.55$ grams of one of the copper(II) salts is reacted with $100\ \mathrm{mL}$ of $0.5\ \mathrm{M}$ sodium hydroxide solution and the reaction goes to completion, and $\mathrm{Cu(OH)_2(s)}$ is formed, what is the anion of this salt, and how many grams of $\mathrm{Cu(OH)_2(s)}$ are formed?
$$(\mathrm{H = 1,\ C = 12,\ N = 14,\ O = 16,\ Na = 23,\ Cu = 64\ :\ g.mol^{-1}})$$
$$\mathrm{CuA_2(aq) + 2NaOH(aq) \rightarrow Cu(OH)_2(s) + 2NaA(aq)}$$
(1) acetate,\ $2.45$ (2) acetate,\ $2.37$ (3) nitrate,\ $2.45$ (4) nitrate,\ $2.37$
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%% Page 23 Chemistry 122-D Page 22

223- Considering the data in the tables below regarding the changes in amount and concentration of $\mathrm{CO_2}$ gas over time in the reaction:
$$\mathrm{CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)}$$
which shows c with respect to a, what are the values of a and b in how many moles per second? (Read the options from right to left, $\mathrm{CO_2 = 44\ g.mol^{-1}}$)

Time (s)	0	10	20	30	40	50
Mass of reaction mixture (g)	65/98	65/32	64/88	64/66	64/55	64/50
Mass of carbon dioxide (g)	0	0/66	1/10	\ldots	\ldots	\ldots

Time (s)	$n(\mathrm{CO_2})$, (mol)	$\Delta n(\mathrm{CO_2})$, (mol)	$\bar{R}(\mathrm{CO_2}) = \dfrac{\Delta n(\mathrm{CO_2})}{\Delta t}$, $(\mathrm{mol.s^{-1}})$
0	0
10	$1/5\times10^{-2}$	$1/5\times10^{-2}$	$1/50\times10^{-3}$
20	$2/5\times10^{-2}$	$1/00\times10^{-2}$	$1/00\times10^{-3}$
30	\ldots	....a....	\ldots\ldots\ldots
40	\ldots	\ldots\ldots\ldots	....b....
50	\ldots	....c....	\ldots\ldots\ldots

(1) $4/3\times10^{-3}$ , $0/22$ (2) $2\times10^{-3}$ , $0/55$
(3) $2/5\times10^{-4}$ , $0/22$ (4) $2\times10^{-4}$ , $0/55$

224- Activation energy of the reaction: $\mathrm{N_2(g) + O_2(g) \rightarrow 2NO(g)}$ is 380 kJ/mol. If the surface temperature difference of reactants and products is 180 kJ/mol and the reaction is exothermic, which of the following statements is correct?

• [A)] For every 0.25 mol of $\mathrm{NO}$ gas consumed, 0.125 mol of $\mathrm{N_2}$ gas is formed and 45 kJ/mol is released.
• [B)] The enthalpy of reaction is $-180$ kJ/mol and the activation energy of the reverse reaction is lower than that of the forward reaction.
• [P)] With the use of a catalyst, the number of particles converted per unit time increases, and the reaction rate increases.
• [T)] If with the use of a catalyst, the activation energy of the forward reaction reaches 190 kJ/mol, the difference in activation energies of the forward and reverse reactions and the products decrease by 50 percent.

(1) A, P (2) B, T (3) A, P, T (4) B, P

225- According to the data in the table below, if 855,000 vehicles travel daily in a city, and each vehicle goes and comes back, on average a distance of 50 km is covered, with a catalytic converter installed in the exhaust of the vehicle, the mass of three pollutants entering the air from the exhaust is reduced per day. Under these conditions, what percentage by mass of the exhaust gases will $\mathrm{CO}$ form?

Chemical formula of pollutant	CO	$\mathbf{C_xH_y}$	NO
Amount of pollutant	\multirow{2}{*}{Without converter}	6/0	1/66	1/03
\cline{1-1}\cline{3-5} (g.km$^{-1}$)	\multirow{2}{*}{Near converter}	0/6	0/06	0/04

(1) $74/14$ , $288/4$
(2) $85/71$ , $288/4$
(3) $74/14$ , $319/6$
(4) $85/71$ , $319/6$
\begin{flushright} Calculation space \end{flushright}
%% Page 24 Chemistry 122-D Page 23

226- In which equilibrium reaction, the sum of stoichiometric coefficients of substances in the balanced equation is greater, and the effect of increasing temperature and pressure is in the same direction?
$$\text{(1)}\quad \mathrm{NH_3(g) + O_2(g) \rightleftharpoons NO(g) + H_2O(g)}, \quad \Delta H < 0$$ $$\text{(2)}\quad \mathrm{Cl_2(g) + H_2O(g) \rightleftharpoons HCl(g) + O_2(g)}, \quad \Delta H < 0$$ $$\text{(3)}\quad \mathrm{C_2H_2Cl_2(g) \rightleftharpoons C_2H_2Cl(g) + HCl(g)}, \quad \Delta H > 0$$ $$\text{(4)}\quad \mathrm{C_2H_4(g) + H_2O(g) \rightleftharpoons C_2H_6(g) + O_2(g)}, \quad \Delta H > 0$$

227- $\mathrm{H_2(g)}$ and $\mathrm{Fe_3O_4(s)}$ are introduced into a vessel at a certain temperature and the following reaction is carried out: $$\mathrm{Fe_3O_4(s) + 4H_2(g) \rightleftharpoons 3Fe(s) + 4H_2O(g)}$$ This equilibrium is established. The equilibrium molar concentration of $\mathrm{H_2O(g)}$ is twice the equilibrium molar concentration of $\mathrm{H_2(g)}$. If $0.6$ mol of iron is present in the equilibrium mixture, approximately what percent by mass of the gas mixture is hydrogen gas at equilibrium? (Read the options from right to left, $\mathrm{H=1,\ O=16\ :\ g.mol^{-1}}$)
(1) $14.8$ , $8$ (2) $5.76$ , $8$ (3) $14.8$ , $16$ (4) $5.76$ , $16$

228- Considering the graph below, which of the following statements about the related reaction is correct?
[Figure: A concentration vs. reaction progress graph showing three curves labeled a, b, and c. Curve a starts at 0.6 and decreases, curve b starts at 0.5 and decreases, and curve c starts near 0 and increases, all reaching equilibrium. The y-axis is labeled $\mathrm{mol \cdot L^{-1}}$ with values 0.1 through 0.6, and the x-axis is labeled reaction progress.]

• [A)] The equilibrium constant of this reaction under experimental conditions is $0.5\ \mathrm{L.mol^{-1}}$.
• [B)] a, b, and c can be $\mathrm{H_2(g)}$, $\mathrm{I_2(g)}$, and $\mathrm{HI(g)}$, respectively.
• [P)] It can correspond to the reaction: $\mathrm{2NO(g) + Cl_2(g) \rightleftharpoons 2NOCl(g)}$, which is reversible.
• [T)] It can be related to the reaction: $\mathrm{COCl_2(g) \rightleftharpoons CO(g) + Cl_2(g)}$, giving a ratio.

(1) A, P (2) A, B (3) B, T (4) P, T

229- How many of the following statements are correct?

• The ion $\mathrm{HCO_3^-}$ is an example of amphoteric compounds.
• The pH of an ammonium ion solution decreases.
• In a healthy person, blood pH changes are within $0.1$ units.
• Based on the Lewis acid-base theory, $\mathrm{SO_4^{2-}(aq)}$ is a stronger base than $\mathrm{CO_3^{2-}(aq)}$.
• In the reaction: $\mathrm{[Fe(H_2O)_6]^{2+}(aq) \leftarrow Fe^{2+}(aq) + 6H_2O(l)}$, water plays the role of a Lewis base -- Brønsted.

(1) 2 (2) 3 (3) 4 (4) 5

230- Which of the following statements are correct?

• [A)] All Arrhenius bases have hydroxide ions ($\mathrm{OH^-}$) in their structure.
• [B)] The Arrhenius definition for acids or bases is limited to aqueous solutions.
• [P)] $0.5$ mol of sulfuric acid with $0.8$ mol of sodium hydroxide produces a neutral solution.
• [T)] The ionization equation of $\mathrm{HNO_2}$ is one-way, but the ionization equation of $\mathrm{HCN}$ is reversible.

(1) A, B (2) B, T (3) A, T (4) P, T
%% Page 25 Chemistry 122-D Page 24

231 – The pH of a sample solution of 0.2 g per liter of weak acid HA with molar mass 20 g/mol equals 4.22. The acid ionization constant at the temperature of the experiment is approximately how much, and what percentage of it is ionized? (Options are from right to left; read $\frac{1}{10^{0.22}} = 0.6$)
$$\left(\frac{1}{10^{0/\text{rr}}} = 0/6\right)$$
(1) $0/6\ ,\ 3/6\times10^{-7}$ (2) $0/4\ ,\ 3/6\times10^{-7}$ (3) $0/7\ ,\ 4/9\times10^{-7}$ (4) $0/5\ ,\ 4/9\times10^{-7}$

232 – Which statement about the compounds with the ``dot-line'' structures below is correct?
$(H=1,\ C=12,\ O=16,\ Br=80\ \text{: g.mol}^{-1})$
[Figure: Two structural formulas labeled (I) and (II); compound (I) contains a carbonyl group (C=O) and compound (II) is a bicyclic structure]

1. The difference in molar mass of the two compounds is 4 g.
2. 3.8 g of compound (II) reacts with 6 g of bromine completely.
3. The two compounds are isomers and compound (I) has a carbonyl functional group.
4. For complete combustion of 7.5 g of compound (I), 14.56 L of oxygen gas is consumed at STP.

233 – Considering the information below, which metal M can have the standard reduction potential?
$$\mathrm{M(s) + Hg^{2+}(aq) \rightarrow Hg(s) + M^{2+}(aq)}$$ $$\mathrm{M^{2+}(aq) + Sn(s) \rightarrow \text{ does not occur}}$$ $$\mathrm{M(s) + Mg^{2+}(aq) \rightarrow \text{ does not occur}}$$ $$\mathrm{M^{2+}(aq) + Mn(s) \rightarrow M(s) + Mn^{2+}(aq)}$$
$\mathrm{E^\circ(Hg^{2+}(aq)/Hg(s)) = +0/85\ V}$
$\mathrm{E^\circ(Sn^{2+}(aq)/Sn(s)) = -0/14\ V}$
$\mathrm{E^\circ(Mg^{2+}(aq)/Mg(s)) = -2/38\ V}$
$\mathrm{E^\circ(Mn^{2+}(aq)/Mn(s)) = -1/18\ V}$
(1) $+0/11$ (2) $-0/11$ (3) $-0/40$ (4) $+1/2$

234 – The sum of stoichiometric coefficients of substances in the oxidation–reduction reaction below is how much, and in the half-reaction of reduction, how many moles of electrons are transferred per mole of oxidizing agent? (Options are from right to left.)
$$\mathrm{Ag(s) + NO_3^-(aq) + H^+(aq) \rightarrow Ag^+(aq) + NO(g) + H_2O(l)}$$
(1) 3 , 14 (2) 4 , 14 (3) 4 , 15 (4) 3 , 15

235 – Regarding the given oxidation–reduction reactions, which statement is incorrect?
$$\mathrm{Ce^{4+}(aq) + e^- \rightarrow Ce^{3+}(aq)\ ,\quad E^\circ = -1/72\ V}$$ $$\mathrm{Cr^{3+}(aq) + 3e^- \rightarrow Cr(s)\ ,\quad E^\circ = -0/74\ V}$$

1. $\mathrm{Ce^{3+}(aq)}$ is the reducing agent in this reaction.
2. The reducing power of $\mathrm{Ce^{4+}(aq)}$ is greater than $\mathrm{Cr(s)}$.
3. $E^\circ$ of the reaction equals $+0/98$ V and it proceeds spontaneously (by itself).
4. The sum of stoichiometric coefficients of substances after balancing the equation is 8, and 3 electrons are exchanged in the reaction.

1) To introduce a particular event

1) Stability of the atom & 2) De Broglie wavelengths of the atom

2) To compare some fun activities

2) $2\text{H}_2(\text{g}) \rightarrow 4\text{H}(\text{g})$
3) $\text{N}_2\text{O}_2(\text{g}) + \text{H}(\text{g}) \rightarrow \text{N}_2\text{O}(\text{g}) + \text{HO}(\text{g})$

3) To trace the origin of Earth Hour

3) Quantization of electron energy in the atom & 4) Difference in intensity of spectral lines of the atom \end{tabular}

4) To describe some ways of saving energy