TEAS Chemistry Practice Test 2

Question – 1

1. The theory which could explain the law of chemical composition is

  • A. Avogadro’s law

  • B. Gay Lussac’s law

  • C. Dalton'[s atomic theory

  • D. Antoine Lavoisier theory

  • E. None of these

  • Answer:C

  • Answer Explanation:Dalton’s atomic theory explains the law of chemical composition. Avogadro’s law states that, at same temperature and pressure, equal volume of gas contains Avogadro number of particles. Gay Lussac’s law explains about gaseous volume. Antoine Lavoisier theory explains about law of conservation of mass.


Question – 2

2. The following reaction proceeds via

  • A. SN1 mechanism

  • B. SN2 mechanism

  • C. Free radical mechanism

  • D. E1 mechanism

  • E. E2 mechanism

  • Answer:C

  • Answer Explanation: N-bromosuccinamide is the best reagent for the bromination of allylic and benzylic position. Generally, NBS in aprotic solvent produces the bromine free radical which attacks the allylic or benzylic position. Therefore, this reaction proceeds via free radical mechanism.


Question – 3

3. In a first order reaction, 25% of the reactant decomposed in 40.5 min. Find the rate constant of the reaction.

  • A. 7.1 X 10-3 min-1

  • B. 0.71 X 10-2 atm-1 min-1

  • C. 5.6 X 10-2 min-1

  • D. 0.56 X 10-2 atm-1 min-1

  • E. 1.2 X 10-2 min-1

  • Answer:A

  • Answer Explanation:Since, the reactant is 25% decomposed in 40.5 min, the remaining reactant is 75%.Rate equation k1=2.303/t) log (a/a-x)a = initial concentrationa-x = remaining concentration of the reactantt = timeTherefore, k1 = (2.303/40.5 min) log (a/0.75a) = 0.05686 log 1.33 min-1k1 = 7.1 X 10-3 min-1


Question – 4

4. When 90Th230 is bombarded with a neutron it produces a product that emits one alpha particle and two positron particles successively, then identify the final product.

  • A. 90Th230

  • B. 90Pu231

  • C. 88Rn227

  • D. 89Ac227

  • E. 90Th227

  • Answer:E

  • Answer Explanation:The reaction proceeds as follows


Question – 5

5. The freezing point of a 0.01 m aqueous solution of NaCl will be

  • A. 0oC

  • B. Below 0oC

  • C. 1oC

  • D. 2oC

  • E. 2.5oC

  • Answer:B

  • Answer Explanation:There is always change (depression) in the freezing point by the addition of solute to a solvent. Therefore, the freezing point of NaCl solution will be lower than that of water. Water’s freezing point is zero degree.


Question – 6

6. ‘No pairing occurs until all orbitals of a given sub level are half filled’. The statement is known as

  • A. Exclusion principle

  • B. Uncertainty principle

  • C. Hund’s rule

  • D. Aufbau principle

  • E. Bohr’s theorem

  • Answer:C

  • Answer Explanation:Exclusion principle states that it is impossible for any two electrons in a given atom to have all the four quantum numbers identical. Hund’s rule states, ‘No pairing occurs until all orbitals of a given sub level are half filled’. Aufbau principle defines that in the ground state of the atoms the orbitals are filled in order of their increasing energies. Uncertainty principle states that the position and momentum of a particle can’t be simultaneously measured with high precision.


Question – 7

7. The ratio of relative abundance of two molecular ion peaks of a chlorine atom in mass spectroscopy is

  • A. M+ : (M+2) = 1:3

  • B. M+ : (M+2) = 3:1

  • C. M+ : (M+2) = 1:2

  • D. M+ : (M+2) = 2:1

  • E. M+ : (M+2) = 1:1

  • Answer:B

  • Answer Explanation:The ratio of relative abundance of two molecular ion peaks of a chlorine atom in mass spectroscopy is M+ : (M+2) = 1:3, because the natural abundance of chlorine is higher than other elements. The natural abundance of chlorine is Cl35- 75.77% and Cl37- 24.23%.


Question – 8

8. Systematic error is also called

  • A. Experimental error

  • B. Random error

  • C. Indeterminate error

  • D. Determinate error

  • E. None of these.

  • Answer:D

  • Answer Explanation:Determinate error is also called systematic error. Determinate errors are those which are known and controllable errors. Ex: Instrumental errors and personal errors.Indeterminate errors are those which are unknown errors. Ex: room temperature. It is also called random errors.


Question – 9

9. Diamond is an example for

  • A. Ionic crystals

  • B. Metallic crystals

  • C. Covalent crystals

  • D. Molecular crystals

  • E. None of these

  • Answer:C

  • Answer Explanation:In diamond, atoms are linked together by continuous system of covalent bonds. In ionic crystals, atoms are held together by ionic bonds. In metallic crystals, atoms are held together by metallic bonds. In molecular crystals, molecules are held together by weak Vander Waal’s forces.


Question – 10

10. What will be its pressure, when 5.2 X 10-3 moles of argon gas is present in a 70mL incandescent light bulb at 250C? (R=0.08205 L atm K-1 mol-1)

  • A. 1.5 atm

  • B. 1.8 atm

  • C. 2.1 atm

  • D. 3.5 atm

  • E. 3.2 atm

  • Answer:B

  • Answer Explanation:By using the ideal gas equation, pressure can be calculated asP = (nRT)/VFrom the given data:n=5.2 X 10-3 mol, T=250C=298K,V=70mL, R=0.08205 L atm K-1mol-1P = (5.2 X 10-3 mol X 0.08205 L atm K-1mol-1 X 298K)/70 mL= (0.121L atm/70mL) X 1000mL/1LP = 1.8 atm


Question – 11

11. The value of Cl-Cl bond distance is found experimentally is equal to 1.98 A0. Find out the radius of the chlorine molecule.

  • A. 3.96 A0

  • B. 0.99 A0

  • C. 3.98 A0

  • D. 0.02 A0

  • E. 0.09 A0

  • Answer:B

  • Answer Explanation:The radius of chlorine molecule,r(Cl) = 0.99 A0


Question – 12

12. Which of the following represents a spontaneous reaction if T = +10 k?

  • A. ??H = +10, ??S = -30

  • B. ??H = +10, ??S = +30

  • C. ??H = -10, ??S = +30

  • D. ??H = -10, ??S = -30

  • E. Both C and D

  • Answer:E

  • Answer Explanation:If the value of enthalpy is negative and the entropy is positive then the reaction is always spontaneous (??H = -10, ??S = +30). If both enthalpy and entropy are negative (??H = -10, ??S = -30), and T < ??H/ ??S then the reaction is spontaneous at low temperature.


Question – 13

13. The relationship between Boyle’s temperature (Tb) and inversion temperature (Ti) is

  • A. Tb = Ti/2

  • B. Tb = Ti/5

  • C. Ti = Tb/27

  • D. 2Ti = Tb

  • E. All the above

  • Answer:A

  • Answer Explanation:Boyle’s temperature in terms of Vander Waals equation Tb = a/bRInversion temperature in terms of Vander Waals equation Ti = 2a/bRTherefore, Tb = Ti/2


Question – 14

14. Choose the correct representation of a galvanic cell from the following.

  • A. Zn2+ | ZnSO4 || CuSO4 | Cu2+

  • B. Zn2+ | Zn(s) | Cu2+ | Cu(s)

  • C. Zn(s) | Zn2+ (aq) || Cu(s) | Cu2+ (aq)

  • D. Zn(s) | Zn2+ (aq) || Cu2+ (aq) | Cu(s)

  • E. Zn(s) | Zn2+ (aq) | Cu2+ (aq) | Cu(s)

  • Answer:D

  • Answer Explanation:While, representing a galvanic cell, the anode half cell should be on the left side and the cathode half cell should be on the right side. The electrode on the left is written in the order: electrode, ion (e.g., Zn, Zn2+) and the electrode on the right is written in the order: ion, electrode (e.g., Cu2+, Cu). A double vertical line should be present between the two half cells, which corresponds to the salt bridge. In the above options, option (d) alone satisfies the above criteria.


Question – 15

15. Which of the following conditions is suitable for analkaline solution?

  • A. [H+] > [OH]

  • B. [H+] = [OH]

  • C. [H+] < [OH]

  • D. [H+] < 10-7 molL-1

  • E. All the above

  • Answer:C

  • Answer Explanation:Generally in an alkaline solution the concentration of oH will be higher than the concentration of H+. Therefore, the condition for the alkaline solution is [H+] < [OH].


Score: 0/10

Leave a Reply

Your email address will not be published. Required fields are marked *