CU-ATS past paper

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CU-ATS CHEMISTRY MOCK EXAM
(Based on real exam)
Presented By Chemystery
55 Multiple choices questions
Given:
- Mass per one mole (g/mol)
H: 1 C: 12 N: 14 O: 16 Na: 23
S: 32 Cl 35.5 K: 39 Ca: 40
- Ideal gas constant
R = 0.082 atm٠L٠mol-1
٠K-1

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CU-ATS MOCK EXAM
Direction: Chose the best alternative.
1. Which ion has the same electron configuration as S2-
?
1) Mg2+
2) Ca2+
3) Ti2+
4) O2-
2. For the following nitrogen containing molecules, which molecule contains nitrogen with lowest oxidation
number?
1) NH3 2) HNO2 3) HNO3 4) NO2
3. Element X is a non-metal. Their valence electrons have principal quantum number = 3. This element has
higher IE1 than S and form ion with same charges as N. What is element X?
1) As 2) P 3) Cl 4) Ga
4. How many grams of an Cr isotope with 6 minutes half-life left after 100 g of this isotope was leave for 0.5
hrs?
1) 50 g 2) 25 g 3) 12.5 g 4) 3.125 g
5. A compound XCl2 has melting point higher than 200 °C. After XCl2 dissolved in water, the solution has pH
equal to 7. What is element X?
1) Ba 2) Mg 3) Fe 4) S
6. How many electrons, protons, and neutrons (in order) in an ion of Al-27?
1) 13, 13, 14 2) 13, 10, 14 3) 10, 13, 14 4) 13, 13, 11
7. Which test tube will contain solid precipitate after they are mixed?
Test tube 1: Lithium + water
Test tube 2: Calcium chloride solid + Potassium nitrate solution
Test tube 3: Magnesium chloride solution + Sodium hydrogen phosphate solution
Test tube 4: Potassium bromide solid + Carbon tetrachloride
1) 1 and 3 2) 3 only 3) 2 and 4 4) 3 and 4

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8. Which choice consist of transition metal and metalloid?
1) Ti, As 2) B, Ge 3) Al, Si 4) V, Zn
9. Which choice present the correct increasing number of lone-pair electron at center atom?
1) H2O< NH3< CH4 2) CH4< SF4 < XeBr4
3) SO2< CO2< NO2 4) BH3< NH3< SO3
10. Which pair of the complex compounds have transition metals with the same oxidation number?
1) K4[Fe(CN)6] and [Cr(OH)2(NH3)4]Cl 2) [TiCl2]SO4 and [Cr(OH)2(NH3)4]Cl
3) [Fe(NH3)4]Cl2 and [CrBr(NH3)5]SO4 4) [CrBr(NH3)5]SO4 and K3[Fe(CN)6]
11. Which compound is NOT correctly matched with its name?
1) ammonia: nitrogen trihydride 2) dry ice: carbon dioxide
3) water: dihydrogen oxide 4) chloroform: carbon tetrachloride
12. Which of the following molecule has smallest bond angle?
1) H2O 2) SO2 3) CO2 4) NH3
13. Which of the following statement is NOT true regarding of diamond?
1) It’s harder than iron. 2) It’s good electrical insulator.
3) It’s square planar geometry 4) It’s an allotrope of carbon.
14. Find the equilibrium expression of: P4(g) + 5O2(g) ⇌ P4O10(s) .

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15. Thermal decomposition reaction of NaHCO3 is occurring in closed container. Which of the following
change will shift equilibrium to the right?
2NaHCO3(s) ⇌ Na2O(s) + 2CO2(g) + H2O(g)
I. Add more NaHCO3(S)
II. Add anhydrous Mg(ClO4)2(s) as water absorber
III. Add dry ice
1) I and II 2) II only 3) I and III 4) II and III
16.After 0.25 mol of NOCl in the 500 ml sealed container undergoes decomposition. At equilibrium 0.2 mol
of NOCl is left. Find the equilibrium constant for the decomposition of NOCl
2NOCl(g) ⇌ 2NO(g) + Cl2(g)
1) 3.15 x 10-3
2) 1.25 x 10-3
3) 2.50 x 10-3
4) 5.00 x 10-3
17. Regarding of the reaction: H2(g) + I2(g) ⇌ 2HI(g) K = 50 at 435°C
Which following change will take place if the concentration of [H2] = [I2] =[HI] = 2.5 x 10-2
?
1) Reaction is at equilibrium, no change of concentration.
2) Equilibrium will shift from left to right.
3) Equilibrium will shift from right to left.
4) Not enough information.
18. Calculate the energy change of the reaction.
Ea of forward reaction
(kJ)
Ea of backward reaction
(kJ)
Step 1 50 80
Step 2 90 40
1) -10 kJ 2) +10 kJ 3) -20 kJ 4) +20 kJ
19. Which following statement(s) is/are NOT true regarding of adding catalyst?
I. The activation energy of reaction will be reduced.
II. The collision frequency of reaction will be increased.
III. The forward reaction rate will be increased but not increase the backward reaction rate.
1) I only 2) III only 3) II and III 4) I and III

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20. For the reaction: 2ICl(g) + H2(g) → I2(g) + 2HCl(g)
Experiment [ICl] [H2] Initial rate (M/s)
1 0.10 0.10 0.0015
2 0.10 0.20 0.0030
3 0.05 0.10 0.00075
Calculate the initial rate of this reaction starting with 0.40 M [ICl] and 0.40 M [H2].
1) 0.0030 M/s 2) 0.0060 M/s 3) 0.0120 M/s 4) 0.0240 M/s
21. Which statement is true?
1) II is an activated complex. 2) The overall reaction is exothermic.
3) This reaction is second order reaction. 4) From II to IV is rate determining step.
22. The highest mol of carbon can be found in ___________.
1) 60 g of glucose (m.w. 180) 2) 200 ml of 0.2 M Na2CO3
3) 3.01 x 1023
atom of C in CaCO3 4) 10 L of CO2(g) at STP
23. Find the mass of PbI2 precipitate formed after 20 ml of 0.4 M Pb(NO3)2 is added to 80 ml of 0.2 M NaI.
(Pb:207, I:127)
1) 1.85 g 2) 2.67 g 3) 3.69 g 4) 5.34 g

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24. Find the concentration of NaNO3, after 100 ml of 0.2 M NaNO3 mixes with 300 ml of 0.4 M NaNO3.
1) 0.24 M 2) 0.28 M 3) 0.35 M 4) 0.38 M
25. What is concentration in molarity of 6.3% w/w HNO3? (density of solution = 1.2 g/ml)
1) 0.12 M 2) 0.48 M 3) 0.95 M 4) 1.20 M
26. The NaNO3 solution is prepared by dissolving 17 g of NaNO3 in water to make 250 ml solution. Calculate
molar concentration of the prepared solution.
1) 0.05 M 2) 0.20 M 3) 0.50 M 4) 0.80 M
27. Calculate density at STP of the air sample that contain 75% of N2 and 25% of O2 approximately.
1) 1.30 g/L 2) 1.78 g/L 3) 2.60 g/L 4) 3.24 g/L
28. An unknown gas sample is collected by water displacement and found that 0.8 grams of collected gas
sample occupied 1.97 L of water at 0.25 atm 27°C. Find the molecular weight of this gas.
1) 28 g/mol 2) 32 g/mol 3) 40 g/mol 4) 64 g/mol
29. The total enthalpy change to form 1 mol of NaCl is -400 kJ/mol, calculate the lattice energy of NaCl from
the given energy change.
Sublimation of Na 100 kJ/mol
Ionization energy of Na 500 kJ/mol
Bond dissociation energy of Cl2 240 kJ/mol
Electron affinity of Cl 350 kJ/mol
1) -30 kJ/mol 2) -370 kJ/mol 3) -550 kJ/mol 4) -770 kJ/mol
30. A 3.8 grams sample of an unknown compound consist of C, H, N and O is burned with excess oxygen to
yield 6.16 g of CO2, 3.68 g of NO2 and 3.24 g of H2O. Which one can be possible formular of this compound?
1) C4H10N4O 2) C5H12N3O 3) C5H14N4O2 4) C7H18N4O2

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31. A balloon is filled with He with pressure 64.8 cmHg has volume equal to 15.2 m3
at 0 °C. How many
grams of He must be added to make the pressure become 72 cmHg while the volume and temperature are kept
constant?
1) 120 g 2) 256 g 3) 2,320 g 4) 2576 g
32. Which of the following 0.1 M solution has the highest boiling point?
1) CaCl2 2) NaCl 3) CH3COOH 4) AlCl3
33. How many grams of pentane(C5H12) must be dissolved in 250 grams benzene to make the freezing point
become 3.0 °C? (Given normal boiling point of benzene = 5.5 °C and Kf of benzene = 5.0 °C)
1) 9.0 g 2) 12.0 g 3) 36.0 g 4) 72.0 g
34. After 6.4 g of an unknown compound was added into 200 g toluene, the freezing point of toluene become
-94.9 °C . Given freezing point of toluene is -94.0 °C and Kf of toluene is 3.6 °C/m, calculate molar mass of
this unknown compound.
1) 25.6 g/mol 2) 64.0 g/mol 3) 128.0 g/mol 4) 256.0 g/mol
35. Which hydrocarbon chain would have highest octane rating?
36. Which reaction can give ester as a major product?
1) Ether + alcohol 2) Ether + carboxylic
3) Carboxylic + alcohol 4) Ketone + alcohol
37. In the mono-chlorination of 2,2-dimethylbutane using Cl2 and light. How many products can be formed?
1) 2 2) 3 3) 4 4) 5

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38. How many hydrogen atoms in the given molecules?
1) 6 2) 7 3) 8 4) 9
39. What type of isomer is found between the given molecules?
1) Stereo isomer 2) Skeletal isomer 3) Functional isomer 4) positional isomer
40. An essential amino acid is one of__________________.
1) Necessary of vitamin production 2) can be synthesized by body
3) Containing element S and N 4) Can be obtained from food only
41. How many structural isomers of C4H10O that can react with Na metal?
1) 2 2) 3 3) 4 4) 5
42. Which of the following is not the allotrope of carbon?
1) diamond 2) graphite 3) C60 4) C2
2-
43. Which one is correct regarding of ozone & ozone layer?
1) Ozone’s chemical formular is CO2.
2) Ozone used as coolant in refrigerator.
3) Ozone can absorb UV light at 200 – 300 nm.
4) Ozone layer is found as the band of several kilometers thickness.

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44. Which one is correct regarding of laboratory protocol?
1) Drinking water is allowed in lab
2) Unused chemical reagent can be put back in their container
3) Wear goggle all the time in lab
4) Dispose chemical reagent into sink or trash bin
45. What is the proper volume reading of liquid inside this burette?
46. The study of preservative in bread has been carried out on white bread and wholewheat bread.
To determine the shelf life of bread, there will be bread sample with preservative and without preservative in
this experiment. The samples are kept under controlled temperature 25 °C and same humidity. The result can
be measured from number of fungi’s colonies on bread after leaved under the same condition for 14 days and
21 days.
Which following statement is true regarding of this experiment?
1) There are four parameters in this experiment.
2) White bread has longer shelf life than wholewheat bread.
3) White bread with preservative has shelf life longer than 14 days.
4) Wholewheat bread with preservative has longer shelf life than 14 days.

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47. What is the oxidation number of oxygen in OF2 and H2O2 in order?
1) +2, -1 2) -2, -1 3) +1, -1 4) +2, -2
48. What is the oxidizing agent in this reaction?
8H+
+ 5Fe2+
+ MnO4
-
Mn2+
+ 5Fe3+
+ 4H2O
1) Fe2+
2) MnO4
-
3) Mn2+
4) Fe3+
49. From the given half reduction potential:
Fe3+
(aq) + e-
→ Fe2+
(aq) E0
= + 0.77 V
Cu2+
(aq) +2e-
→ Cu(s) E0
= + 0.34 V
Cd2+
(aq) +2e-
→ Cd(s) E0
= - 0.40 V
Fe2+
(aq) +2e-
→ Fe(s) E0
= - 0.45 V
Construct the cell diagram from the galvanic cell of half-cell 1M Fe2+
and 1M Fe3+
solution (Pt electrode) with
a half-cell of Cd plate inCdSO4 solution.
1) Pt(s) l Fe3+
(aq) (1M), Fe2+
(aq) (1M) ll Cd2+
(aq) (1M) l Cd(s)
2) Cd(s) l Cd2+
(aq) (1M) ll Fe3+
(aq) (1M), Fe2+
(aq) (1M) l Pt(s)
3) Fe(s) l Fe2+
(aq) (1M) ll Cd2+
(aq) (1M) l Cd(s)
4) Cd(s) l Cd2+
(aq) (1M) ll Fe2+
(aq) (1M) l Fe(s)
50. Why aluminum does not corrode as does iron?
1) Impurity in aluminum prevent corrosion
2) Aluminum does not react with O2
3) Aluminum oxide coat on surface of aluminum
4) Aluminum is harder to be oxidized than iron
51) What is the pH of 5 x 10-3
M Ba(OH)2 solution?
1) 11.3 2) 12.0 3) 2.7 4) 2.0
52) What is the pOH of the 0.01 M weak mono protic acid with Ka = 1 x 10-8
?
1) 4.0 2) 5.0 3) 9.0 4) 10.0

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53) Which center atoms of the following molecules can’t act as Lewis acid?
1) CO2 2) BCl3 3) AlCl3 4) H2O
54) Which of the following mixtures will NOT form a buffer solution?
1) NaNO2 and HNO2 2) HF and NaF
3) NaNO3 and HNO3 4) NH3 and (NH4)2SO4
55) A mixture solution containing HCl and the weak acid HClO2 has a pH of 2.4. Enough KOH(aq) is added to
this solution until the pH of solution become 10.5. The amount of which of the following species increases as
the KOH(aq) is added?
1) Cl-
(aq) 2) H+
(aq) 3) ClO2
-
(aq) 4) HClO2(aq)
Answer Key can be checked in FB: Chemysteryz
Contact for tutorial course Line id: mheeyakz

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Direction: Mark (X) on the answer sheet provided for items 1-55.
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