ข้อสอบ CU-ATS Chemistry พร้อมเฉลย สำหรับฝึกฝนก่อนสอบ

1. From the list of standard electrode potentials shown below, what is the strongest oxidizing and reducing reagents?

VO²⁺+ 2H⁺+ e^- ⇌ V³⁺+ H₂O E^o= + 0.34 V

S₂O₃^2-+ 6H⁺+ 4e^- ⇌ 2S + 3H₂O E^o= + 0.47 V

ClO^- + H₂O + 2e^- ⇌ Cl^-+ 2OH^- E^o= + 0.89 V

VO₂⁺+ 2H⁺+ e^- ⇌ VO²⁺+ H₂O E^o= + 1.00 V

	Strongest oxidizing agent	Strongest reducing agent
1)	VO₂⁺	S₂O₃^2-
2)	S₂O₃^2-	VO²⁺
3)	VO²⁺	ClO^-
4)	ClO^-	V³⁺
5)	VO₂⁺	V³⁺

1

2

3

4

5

2. The graph above shows a relationship between vapor pressure and the temperature of ether, water, and mercury. Which substance has the lowest surface tension?

Diethyl ether

Water

Mercury

More than two substances have the same lowest surface tension

Insufficient information

3

1 and 3

1 and 4

2 and 3

only 4

All of the above is not correct

4. A balloon has a volume of 20.0 dm³ at the mean sea level (1 atm and 27 °C). It rises to the top of the mountain, which is 1 km higher from the mean sea level, and explodes. At the top of the mountain, the external pressure is 0.5 atm and the temperature reduces to -23 °C. What is the largest volume of the balloon at the top of the mountain?

16.7 dm³

33.3 dm³

66.7 dm³

133.3 dm³

333.3 dm³

5. What is the pH value of basic salt of 1.0 M Na₂X, when K_a1 and K_a2 of H₂X = 10^-8 and 10^-10, respectively?

8

9

10

11

12

6. Which of the following substances has the highest boiling point? (Relative atomic mass of H = 1, C = 12, O = 16)

0.25 g of Lactose (C₁₂H₂₂O₁₁) in 100 cm³ of water

0.25 g of Galactose (C₆H₁₂O₆) in 50 cm³ of water

0.25 g of Ribose (C₅H₁₀O₅) in 25 cm³ of water

Pure water

All of the above are equal boiling point

7. A reversible reaction A + B ⇌ 2C has the equilibrium constant, K, equals to 9. A and B have the same initial concentrations of 0.02 M. What is the concentration of B at equilibrium?

0.0012 M

0.008 M

0.01 M

0.012 M

0.022 M

8. Dimethandrolone undecanoate (DMAU) is a compound being developed for use as a potential male hormonal contraceptive, specifically as a birth control pill for men. From the molecular structure of DMAU shown below, which geometry can be found the most in carbon atoms of this molecule?

Linear

Bent

Trigonal planar

Trigonal bipyramidal

Tetrahedral

9. A student carried out an experiment by adding an unknown substance B to a test-tube containing Benedict’s solution. When the test-tube was heated, the solution remained blue. In a separate test-tube containing dilute hydrochloric acid, substance B was added to the test-tube, which was then heated in boiling water for 10 minutes. The solution was neutralised before being added to a test-tube containing Benedict’ solution, which was then heated. Brick red precipitates were observed. What could the unknown B be?

Honey

Milk

Corn syrup

Tapioca flour

None of the above

10. Element X has a relative atomic mass 14 times greater than that of tritium and the number of neutrons 22 times greater than that of deuterium. What is the property of the oxide of X?

Acidic

Basic

Neutral

Amphoteric

None of the above

11. What is the electronic configuration of cobalt in the compound [Co(NH₃)₄SO₄]NO₃?

(Proton number of Co = 27)

span>[Ar] 3d⁵

span>[Ar] 3d⁶

span>[Ar] 3d⁷

span>[Ar] 3d⁸

span>[Ar] 4s²

12. What is the density, in the unit of kg m^-3, of this metal with the mass of 31.5 g?

3.15 kg m^-3

6.3 kg m^-3

3,150 kg m^-3

6,300 kg m^-3

630 kg m^-3

13. The table below shows some radioisotopes with their half-life.

Radioisotope	Half-life (days)
Cobalt-57	271.79
Einsteinium-254	275.7
Berkelium-249	330
Californium-248	333.5

Mass of oisotope Z decreases from 5.44 g to 0.34 g after 3.655 years.

Given that a year has 365 days. What is the identity of the radioisotope Z?

Cobalt-57

Einstenium-254

Berkelium-249

Californium-248

Cacium-42

14. Which five gases are compressed into each balloon which contains 2 liters. Which one of the following gases makes the balloons still the largest size when hanging each balloon at room temperature after passing two weeks? (Relative atomic mass of H = 1, He = 4, Ne = 10, N = 14, O = 16, Ne = 20)

O₂

N₂

He

Ne

H₂

15. Which of the following statements about absolute zero is NOT TRUE?

The absolute zero is the temperature at which molecular motion ceases

The absolute zero is the temperature where nothing could be colder and no heat energy remains in a substance

The temperature at absolute zero is -273.15 C

The entropy of all substances at absolute zero is exactly equal to zero

All of the above is true

16. What is the major difference between DNA and RNA?