MCQs - set II- Relative Molecular mass

MCQs Set 2
This is the second set of MCQs..you can write to me at poonamlphs@gmail.com for any queries.

1. Which of the following aqueous solutions will boil at the highest temperature? Note: all of the salts listed below are completely soluble in water.
1. A 0.10 m solution of NaCl.
2. A 0.10 m solution of Na₂SO₄.
3. A 0.10 m solution of Na₃PO₄.
4. A 0.10 m solution of K₂SO₄.
2. Which of the following pairs of properties are both colligative properties?
1. freezing point, density
2. freezing point, vapour pressure
3. boiling point, colour
4. vapour pressure, molality
3. Which of the following concentration units changes with temperature?
1. molality
2. mole fraction
3. molarity
4. mass percent
4. What is the mole fraction of water in a solution that contains 18 g of water (MW = 18 g/mol) and 92 g of ethyl alcohol (MW = 46 g/mol)?
1. 0.16
2. 0.33
3. 0.50
4. 0.87
5. What is the vapor pressure of water over a solution prepared by dissolving 100 g of sucrose (MW = 342 g/mol) in 225 g of water (MW = 18.0 g/mol) at 90^oC? The vapor pressure of pure water at 90^oC is 526 torr.
1. 0.079 torr
2. 514 torr
3. 539 torr
4. 1,184 torr
6. The melting point of pure benzene is 278.70 K and the molal freezing point depression constant is 4.90 K/molal. When 4.20 g of an unknown solute is added to 100 g of benzene, the freezing point of the solution is 277.60 K. What is the molecular weight of the unknown?
1. 226 g/mol
2. 187 g/mol
3. 128 g/mol
4. 18.7 g/mol
7. Calculate the mole fraction of acetone in the vapour above a solution prepared by dissolving 0.50 moles of acetone (P^o = 345 torr) in 1.00 mole of ethanol (P^o = 59.8 torr) at 25^oC.
1. 0.33
2. 0.50
3. 0.67
4. 0.74
8. When a solution is prepared from two volatile liquids with different vapor pressures, the vapour pressure of the solution will be:
1. greater than the vapour pressure of each of the pure liquids.
2. less than the vapour pressures of each of the pure liquids.
3. the sum of the vapour pressure of the two pure liquids.
4. somewhere between the vapor pressures of the pure liquids.
9. Which of the following statements about colligative properties is TRUE?
1. Both freezing point and boiling point INCREASE when a non- volatile solute is added to a solvent.
2. Both vapor pressure and boiling point DECREASE when a non- volatile solute is added to a solvent.
3. Colligative properties depend only upon the NUMBER of solute particles in a solution and not upon their identity.
4. None of the above statements is true.
10. The molal elevation constant is the ratio of elevation in boiling point to :-
1. Molarity
2. Molality
3. Mole fraction of the solute
4. Mole fraction of the solvent
11. A 7.00 g sample of a nonelectrolyte is dissolved in 45.0 g of water. If pure water freezes at 0.00^oC and the solution freezes at -2.56^oC, calculate the molecular weight of the nonelectrolyte. For water, k_f = 1.86 ^oC/m.
1. 11.3
2. 62.1
3. 113
4. 345
12. Which of the following aqueous solutions would have the HIGHEST freezing point? Note that all of these salts are completely soluble in water.
1. a 0.10 molal solution of sodium chloride (NaCl)
2. a 0.10 molal solution of magnesium chloride (MgCl₂)
3. a 0.10 molal solution of iron chloride (FeCl₃)
4. a 0.10 molal solution of ammonium phosphate ((NH₄)₃PO₄)
13. For a nonvolatile solute dissolved in a volatile solvent, the vapor pressure, freezing point, and boiling point:
1. are all higher for the solution than for the pure solvent.
2. change differently, with vapor pressure increasing and boiling and freezing points decreasing.
3. change differently, with boiling point increasing and vapour pressure and freezing point decreasing.
14. 0.400 mole of CCl₄ and 0.600 mole of CHCl₃ are mixed at 43^oC. The vapour pressure of pure CCl₄ at this temperature is 0.354 atm and the vapour pressure of pure CHCl₃ at this temperature is 0.526 atm. What is the vapour pressure of the solution?
1. 0.285 atm
2. 0.423 atm
3. 0.457 atm
4. 0.526 atm
15. A commercial vinegar was found to contain 4.1% BY MASS of acetic acid (CH₃COOH) in water. If the density of the vinegar is 1.01 g/mL, calculate the MOLARITY of the vinegar.
1. 0.38
2. 0.69
3. 1.1
4. 4.1
16. Calculate the PERCENT BY MASS of hydrogen peroxide (H₂O₂, MW = 34.0 g/mole) in a 5.88 M solution of H₂O₂ in water. The density of the solution is 1.00 g/mL.
1. 3.00%
2. 5.00%
3. 20.0 %
4. 30.0 %
17. Solutions which distil out without any change in composition are called:-
1. Amorphous
2. Azeotropic mixture
3. Super saturated
4. Ideal
18. Aqueous solutions of 0.004M sodium sulphate and 0.01M glucose are isotonic. The degree of dissociation of sodium sulphate is :-
1. 25%
2. 60%
3. 75%
4. 85%
19. The molal elvation constant is the ratio of elevation in boiling point to :-
1. Molarity
2. Molality
3. Mole fraction of the solute
4. Mole fraction of the solvent

20.  When 20g of Naphthoic acid(C₁₁H₈O₂) is dissolved in 50g of benzene

(Kf = 1.72Kkg/mol) , a freezing point depression of 2K is observed. The van’t Hoff factor is:-

1. 0.5
2. 1
3. 2
4. 3

 

First set of Chemistry MCQs

I intend to post 20 MCQs everyday....You all have just revised the complete syllabus...so it should take just 10 minutes to solve them...

Multiple Choice questions

1. Which sample of water will have the lowest vapour pressure:

(1)   100ml at 50°C

(2)   200ml at 30°C

(3)   300ml at 40°C

(4)   400ml at 20°C

(5)   100ml at 45°C

     2.  Which type of matter is composed of two or more different elements that are chemically combined in a definite ratio?

(1)   a solution

(2)   a compound

(3)   a colloidal solution

(4)   a homogeneous mixture

(5)   a heterogeneous mixture

       3.  Which list of particles is in order of increasing mass?

               (1) proton ®electron ®alpha particle

               (2) proton ®alpha particle ®electron

               (3) electron ® proton ®alpha particle

               (4) alpha particle ®electron ®proton

               (5) alpha particle ®proton ®electron

      4.  How many ozone molecules are in 3.20 g of O₃?

(1)         4.0 × 10²²

(2)         6.0 × 10²²

(3)         1.2 × 10²³

(4)         6.0 × 10²³

(5)         4.0 × 10²¹

5.  1.0 M aqueous solutions of AgNO₃, Cu(NO₃)₂ and Au(NO₃)₃ are electrolyzed

      in the apparatus shown, so the same amount of electricity passes through each     solution. If 0.10 moles of solid Cu are formed how many moles of Ag and Au are formed?

                                   

(1)         0.10 moles Ag, 0.10 moles Au

(2)         0.05 moles Ag, 0.075 moles Au

(3)         0.05 moles Ag, 0.15 moles Au

(4)         0.02 moles Ag, 0.02 moles Au

(5)         0.20 moles Ag, 0.067 moles Au

    6.   When forming covalent bonds, which atom can have more than eight valence electrons?

(1)         H

(2)         N

(3)         Na

(4)         F

(5)         Cl

   7.    Which diatomic molecule has the shortest bond length?

(1)         N₂

(2)         Cl₂

(3)         O₂

(4)         F₂

(5)         S₂

    8. Which species is nonpolar?

(1)         HCl

(2)         OCl₂

(3)         H₂O

(4)         NCl₃

(5)         CCl₄

 9. In which species are all the carbon atoms considered to be sp² hybridized?

(1)         C₂H₂

(2)         C₄H₈

(3)         C₃H₈

(4)         C₆H₆

(5)         C₄H₁₀

     10. How many sigma bonds does a molecule of ethene have?

(1)         1

(2)         4

(3)         5

(4)         7

(5)         3

11. Which species is isoelectronic with NO₂⁺?

(1)         N₂O

(2)         NO₂^–

(3)         NH₂^–

(4)         SO₂

(5)         SO₃

12. The concept of resonance is used to describe molecular structures which

(1)         oscillate between two structures.

(2)         have mirror images.

(3)         can be isolated in several isomeric forms.

(4)         have more than one possible Lewis structure.

(5)         Have free rotation about single bonds

13. What are the signs of ∆H° and ∆S° for a reaction that is spontaneous at all                                            temperatures?

                                    ∆H°                 ∆S°

(1)                     +                      +

(2)                     +                      –

(3)                     –                      +

(4)                      –                     –

(5)              Both (1) and (3)

14. Which change occurs with the largest increase in entropy at 25°C?

(1)         Br₂(l) → Br₂(g)

(2)         H₂O(l) → H₂O(s)

(3)         C(graphite) → C(diamond)

(4)         H₂O(s) → H₂O(l)

(5)         HCl(g) + H₂O(l) → H₃O⁺(aq) + Cl^–(aq)

15. Which combination of solutions of HCl and NaOH would produce the largest ∆T?

(1)         50 mL of 1 M HCl with 50 mL of 1 M NaOH

(2)         50 mL of 2 M HCl with 50 mL of 2 M NaOH

(3)         100 mL of 1 M HCl with 50 mL of 2 M NaOH

(4)         100 mL of 1 M HCl with 100 mL of 1 M NaOH

(5)         100 mL of 1 M HCl with 50mL of 1 M NaOH

16.  How is the vapor pressure of a liquid in a closed container affected when the quantity of      liquid is doubled at constant temperature?

(1)         The vapor pressure increases.

(2)         The vapor pressure decreases.

(3)         It cannot be determined

(4)         The vapor pressure remains the same.

(5)         The vapor pressure may increase or decrease,depending on the liquid.

17. Oxygen, which is 16 times as dense as hydrogen, diffuses

(1)         1/16 times as fast.

(2)         1/4 times as fast.

(3)         4 times as fast.

(4)         16 times as fast.

(5)         8 times

18. The mass of 560 cm³ of a gas at 0°C and 1 atm is 1.60g.Which gas could it be?

(1)         O₂

(2)         CO₂

(3)         SO₂

(4)         N₂

(5)         Cl₂

19. What is the correct order when the substances O₂, H₂O,OF₂, and H₂O₂ are arranged in order of increasing oxidation number for oxygen?

(1)         O₂, H₂O, OF₂, H₂O₂

(2)         H₂O, H₂O₂, O₂, OF₂

(3)         H₂O₂, O₂, H₂O, OF₂

(4)         OF₂, O₂, H₂O₂, H₂O

(5)         H₂O, OF₂, H₂O₂ ,O₂

20. Under which conditions will a gas behave most ideally?

(1)         0°C and 1 atm

(2)         low P and high T

(3)         low P and low T

(4)         high P and low T

(5)         high P and high T

Chemistry MCQs for entrance examinations

The Chemistry Paper was very good...I am very happy the many questions were from the model papers..Thank you very much for all the motivation...
I am now going to upload  MCQs for entance examinations...Please keep viewing the blog for more updates...

The final tip before the Chemistry Examination

The most important tip before the Chemistry Examination is that you must have atleast seven to eight hours sleep. Wish you all the very best for the Examination... I am confident that all of you are going to do very well.