Cisco
CompTIA
ISC
EC-Council
EXIN
Fortinet
ITIL
Juniper
Microsoft
VMware
Avaya
SAP
Google
NVIDIA
Salesforce
Amazon
Palo Alto Networks
ISC2
Splunk
ServiceNow
All Vendors
  2. Home
  3. Exams
  4. Test Prep
  5. MCAT Test

Test Prep MCAT Test Exam
Medical College Admission Test: Verbal Reasoning, Biological Sciences, Physical Sciences, Writing Sample (Page 13 )

Updated On: 12-Jan-2026
Page 13 of 164
PDF with 811 Questions

A researcher investigated the equilibrium between CO2, C, and CO as a function of temperature. The equation is given below:

Carbon dioxide, at 298 K and 1 atm, and an excess of powdered carbon were introduced into a furnace, which was then sealed so that pressure would increase as the temperature rose. The furnace was heated to, and held constant at, a predetermined temperature. The pressure within the furnace chamber was recorded after it had remained unchanged for one hour. The table below shows the pressures recorded for a series of temperatures together with the pressures expected if no reaction had taken place.
Table 1


Which of the following shows the correct Lewis structure of carbon monoxide?

  1. Option A
  2. Option B
  3. Option C
  4. Option D

Answer(s): C

Explanation:

The first thing that should be done is to determine which choices have the proper number of valence electrons.
Carbon monoxide must have a total of 10 electrons: six from the oxygen and four from the carbon. Choice B and choice D can be eliminated because they both have 12 electrons.
In choice A, the carbon has one pair of unbonded electrons, plus four more electrons in the double bond. This gives the carbon a total of only six electrons in its valence shell, so the carbon doesn't have a complete octet, and choice A must be wrong. Choice C shows the correct Lewis structure for carbon monoxide: each atom has a complete octet, and there is a total of ten electrons.



A researcher investigated the equilibrium between CO2, C, and CO as a function of temperature. The equation is given below:


Carbon dioxide, at 298 K and 1 atm, and an excess of powdered carbon were introduced into a furnace, which was then sealed so that pressure would increase as the temperature rose. The furnace was heated to, and held constant at, a predetermined temperature. The pressure within the furnace chamber was recorded after it had remained unchanged for one hour. The table below shows the pressures recorded for a series of temperatures together with the pressures expected if no reaction had taken place.
Table 1

How are the values of Pe calculated?

  1. (T/273)(1 atm)
  2. (T/298)(1 atm)
  3. [(T ­ 273)/273](1 atm)
  4. [(T ­ 298)/298](1 atm)

Answer(s): B

Explanation:

Pe as the table explains, is the expected pressure at each temperature if no reaction had taken place. When the carbon dioxide is introduced into the furnace chamber, it is at a pressure of 1 atmosphere and a temperature of 298 K. Above 298 K, Pe is greater than 1 atmosphere because, at constant volume, the pressure increases as the temperature increases. Since Pe is the pressure if no reaction had taken place, any change in the number of moles of gas present does not have to be considered. Since the pressure of a gas is directly proportional to its temperature in Kelvins, the ratio of the EXPECTED pressure to the original pressure of 1 atmosphere must be equal to the ratio of the temperature of the trial to the original temperature of 298 K. The equation is as follows:
Pe /(1 atm) = T/298

Solving for Pe yields answer choice B.



A researcher investigated the equilibrium between CO2, C, and CO as a function of temperature. The equation is given below:

Carbon dioxide, at 298 K and 1 atm, and an excess of powdered carbon were introduced into a furnace, which was then sealed so that pressure would increase as the temperature rose. The furnace was heated to, and held constant at, a predetermined temperature. The pressure within the furnace chamber was recorded after it had remained unchanged for one hour. The table below shows the pressures recorded for a series of temperatures together with the pressures expected if no reaction had taken place.
Table 1

If 0.6 g of elemental carbon are consumed during a trial, how many grams of CO are produced?

  1. 0.8
  2. 1.4
  3. 1.6
  4. 2.8

Answer(s): D

Explanation:

Since carbon has a molar mass of 12 grams, a tenth of a mole would be 1.2 grams, and the 0.6 grams stated in the question is one twentieth of a mole. The equation given in the passage shows that for every one mole of carbon consumed, two moles of CO are produced. So, if one twentieth of a mole of carbon is consumed, two twentieths, or one tenth, of a mole of CO will be produced. One tenth of the molar mass of CO, 28 grams, is 2.8 grams. Therefore, choice D is the correct response



Light traveling from air into a new medium is refracted away from the normal. This medium might be:

  1. glass.
  2. water.
  3. steel.
  4. a vacuum.

Answer(s): D

Explanation:

The question is about refraction, which is the process that bends light as it travels from one medium into another. Snell's law n1sin 1 = n2 sin 2 describes this process, where n1 and n2 are the indices of refraction of the two media, and 1 and 2 are the angles that the light rays make with the normal to the interface between the two mediA. This law predicts that light traveling into a medium with a higher index of refraction will be refracted towards the normal. Light traveling into a medium with a lower index of refraction will be refracted away from the normal. In the question, the light is refracted away from the normal, so the new medium must have an index of refraction lower than air. The vacuum has the lowest index of refraction possible, n = 1, so choice D is correct.
Steel is opaque, so light will not travel through it at all. The steel surface will absorb or reflect light, not refract it, so choice C is wrong. Water and glass both have indices of refraction that are higher than air, so both choices A and B are wrong. Note that even if you did not remember whether higher indices cause refraction towards or away from the normal, you could have eliminated choices A and B because they both would bend the light in the same direction, and both cannot be right.



Which expression correctly expresses the Ksp of a solution of XmYn?

  1. [Xm+]n [Yn-]m
  2. [Xn+]m [Ym-]n
  3. ([Xm+]n [Yn-]m) / X
    mYn
  4. ([Xn+]m [Ym-]n) / X
    mYn

Answer(s): B

Explanation:

The Ksp, or solubility product constant, is found by multiplying together the concentrations of the dissociated ions, each raised to a power equal to the number of ions in one formula unit of the salt. When a mole of the salt, XmYn, dissolves, m moles of Xn+ ions and n moles of Ym- ions enter solution. So, the coefficient of X is , and the coefficient of Y is n. The expression is as follows:
m
Ksp = [Xn+]m [Ym-]n
Choice B is therefore the correct answer. Choice A is wrong because it has the coefficients reversed. Choice C and choice D can be eliminated because the Ksp is not a fraction.



Viewing page 13 of 164
Viewing questions 61 - 65 out of 811 questions



Post your Comments and Discuss Test Prep MCAT Test exam prep with other Community members:

Join the MCAT Test Discussion