Please help me with these MCQ, choose the right answer by highlighting: 1. A gas

Question

Please help me with these MCQ, choose the right answer by highlighting:

1.      A gas bottle contains 0.800 mol of gas at 730 mm Hg pressure. If the final pressure is 1.15 atm, how many moles of gas were added to the bottle?

a) 0.958 mol

b) 0.0012 mol

c) 0.158 mol

d) 0.0668 mol

QUESTION 2

1.      How many grams of H2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?

a) 823 g

b) 2.16 g

c) 1.08 g

d) 0.542 g

  

QUESTION 3

Under which of the following conditions would one mole of Ne have the highest entropy, S?

a) 29°C and 26 L

135°C and 34 L

c) 29°C and 34 L

d)

135°C and 26 L

QUESTION 4

Which of the following forms a molecular solid?

a) C, graphite

b) CaCl2  

c) C9H8O4

d) palladium

QUESTION 5

When ethylene glycol, HOCH2CH2OH, is added to the water in an automobile radiator, the effect is to

a) raise the boiling point and raise the freezing point.

b) raise the boiling point and lower the freezing point.

c) lower the boiling point and lower the freezing point.

d) lower the boiling point and raise the freezing point.

QUESTION 6

For a process to be at equilibrium, it is necessary that

a)?Ssys = 0.

?Ssys = -?Ssurr.

c) ?Ssys = 0 and ?Ssurr = 0.

d) ?Ssys = ?Ssurr.

  

QUESTION 7

Which of the following is most likely to have the highest viscosity at 25°C?

a) HOCH2CH2OH

C7H8

c) C3H7OH

C6H14

  

QUESTION 8

   Use the diagram below to answer the following questions.


Melting occurs along the

a) AC line.

b) CB line.

c) CD line.

d) All of these

QUESTION 9

For the conversion of ice to water at 0°C and 1 atm,

a) ?G is negative, ?H is positive, and ?S is negative.

b) ?G is zero, ?H is positive, and ?S is negative.

?G is positive, ?H is zero, and ?S is positive.

?G is zero, ?H is positive, and ?S is positive.

QUESTION 10

A supercritical fluid refers to a substance

a) that is in the liquid crystal state.

b) above both its critical temperature and its critical pressure.

c) at its triple point.

d) with a viscosity of zero.

QUESTION 11

Calculate the freezing point of a solution of 30.0 g methyl salicylate, C7H6O2, dissolved in 800. g of benzene, C6H6. Kf for benzene is 5.10°C/m and the freezing point is 5.50°C for benzene.

a) 1.56°C

b) 7.06°C

c) 3.93°C

d) -1.56°C

  

QUESTION 12

Which of the following gases has the lowest average speed at 25°C?

a) C2H6

b) F2

PH3  

H2Se

  

QUESTION 13

When a narrow diameter glass tube is inserted into a body of water, water rises in the tube and its surface inside is concave upwards. Which statement, concerning the strength of the intermolecular forces between glass and water molecules compared to those between water molecules, is accurate?

a) The forces of attraction between the glass and water are the same as those in water.

b) The forces of attraction between the glass and water are weaker than those in water.

c) The forces of attraction between the glass and water are stronger than those in water.

d) Intermolecular forces are irrelevant to this situation.

  

QUESTION 14

According to the kinetic molecular theory, the pressure of a gas in a container will decrease if the

a) number of moles of the gas increases.

b) volume of the container decreases.

c) temperature of the gas decreases.

d) number of collisions with the container wall increases.

  

QUESTION 15

   The figure represents the spontaneous deposition of iodine in which iodine vapor, I2(g), becomes crystalline iodine solid I2(s): I2(g): ? I2(s). What are the signs (+ or -) of ?H, ?S, and ?G for this process?

a) ?H = +, ?S = +, ?G = +

b) ?H = +, ?S = +, ?G = -

c) ?H = -, ?S = -, ?G = +

d) ?H = -, ?S = -, ?G = -

a) 0.958 mol

b) 0.0012 mol

c) 0.158 mol

d) 0.0668 mol

Explanation / Answer

1) Initial number of moles, n1 = 0.800 mol
Initial pressure, P1 = 730 mm Hg
   Final pressure, P2 = 1.15 atm = 760 x 1.15 mm Hg = 874 mm Hg
   Final number of moles, n2 = ?
From ideal gas equation, P1/n1 = P2/n2
   n2 = P2n1/P1 = 874 mm Hg * 0.8 mol / 730 mm Hg = 0.958 mol
Number of moles of gas added = 0.958 - 0.8 = 0.158 mol

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