question
stringlengths 7
1.06k
| op2
stringlengths 2
358
| op1
stringlengths 2
370
| op4
stringlengths 2
399
| category
stringclasses 6
values | op3
stringlengths 2
355
| exam_id
int64 1
210
| cop
int64 0
4
| unique_id
stringlengths 36
36
| year
stringclasses 5
values |
|---|---|---|---|---|---|---|---|---|---|
All ideal gases at a temperature of 25 ºC and pressure of 10 bar have the same:
|
Density.
|
Number of molecules per unit of volume.
|
Number of moles.
|
Chemistry
|
Molecular mass.
| 161 | 1 |
b4754479-efbf-4318-8e8d-b918be92ace5
|
2020
|
The chemical reaction: A(g) ↔ 2 B (g) is exothermic and is in equilibrium under given P and T conditions. The equilibrium constant is K0. When the temperature increases:
|
K0 decreases.
|
K0 increases.
|
It cannot be predicted what will happen, it will depend on the value of the standard entropy change.
|
Chemistry
|
K0 does not vary.
| 162 | 2 |
a4dcece2-6859-4c4b-ac7d-4ec77ef3857e
|
2020
|
A gas can be considered to behave in an ideal manner:
|
At high pressures and high temperatures.
|
At high pressures and low temperatures.
|
At low pressures and low temperatures.
|
Chemistry
|
At low pressures and high temperatures.
| 164 | 3 |
42bab228-765d-498c-9525-72bb929428f9
|
2020
|
The Clausius-Clapeyron equation is strictly adhered to in the phase transition:
|
Freezing of cyclohexane at 6.5 ºC.
|
Conversion of diamonds under pressure.
|
Conversion of diatomic oxygen, O2 (g), into triatomic ozone, O3 (g).
|
Chemistry
|
Sublimation of ice in the freezer.
| 167 | 3 |
9e585d77-877a-49a4-b395-a86cb303fccc
|
2020
|
In which units is the rate constant of a chemical reaction expressed?
|
If the overall order of the reaction is one, in mol.L-1s-1.
|
If the reaction is of zero order, in mol.L-1s-1.
|
If the overall order of the reaction is three, in s-1.
|
Chemistry
|
If the reaction is of zero order with respect to one reagent and of first order with respect to another, in mol.L-1s-1.
| 168 | 1 |
b27cb1f1-9649-41e5-b13b-3bf22ad51a1a
|
2020
|
A gas can be liquefied through isothermal compression:
|
At its critical temperature.
|
At temperatures higher than its critical temperature.
|
At any temperature.
|
Chemistry
|
At temperatures lower than its critical temperature.
| 169 | 3 |
da895272-9251-4640-b539-488daebdc35f
|
2020
|
Non-ideal (real) gases tend to behave ideally at :
|
Low temperatures and high pressures.
|
Low temperatures and low pressures.
|
High temperatures and high pressures.
|
Chemistry
|
High temperatures and low pressures.
| 170 | 3 |
74cbcaa7-477f-4828-9469-dcc26997d09d
|
2020
|
Which of the following statements can be proven from the second law of thermodynamics:
|
The entropy of an isolated system must remain constant.
|
In a closed system, equilibrium corresponds to the position of maximum entropy of the system.
|
The entropy of a closed system can never decrease.
|
Chemistry
|
For a system enclosed in impermeable adiabatic walls, the entropy of the system is maximized at equilibrium.
| 171 | 4 |
4ef89137-cbcc-42de-9476-d2b30319b349
|
2020
|
If under certain conditions the fugacity of a gas is greater than the pressure, what would we say about the interactions between the gas molecules?
|
Repulsive interactions dominate.
|
The attractive and repulsive interactions are balanced.
|
Attractive interactions dominate.
|
Chemistry
|
The gas is ideal, there are no interactions between the gas molecules.
| 172 | 2 |
1233868a-c9d1-40f1-9100-edc3040966fa
|
2020
|
In a reactor where a chemical reaction takes place between ideal gases, how does the isochoric addition of an inert gas at constant temperature affect the equilibrium?
|
Increases the conversion of reactants into products.
|
It does not modify the equilibrium conversion.
|
Increase the concentration of the reactants.
|
Chemistry
|
Decreases the conversion of reactants into products.
| 173 | 1 |
54ee620c-ba5c-44bc-8a01-85e244e61bc9
|
2020
|
In an electrolysis experiment, an electric current of 0.10 A circulates through a 10cm2 surface electrode and through a solution with a conductivity of 0.010 Ω-1cm-1. The intensity of the electric field is:
|
100 V cm-1.
|
0.10 A.
|
100 J C-1.
|
Chemistry
|
100 N C -1.
| 174 | 3 |
efd163f9-ed1c-4dfb-a234-0317ee52ced7
|
2020
|
What is the Langmuir isotherm, in the context of adsorption on solid surfaces?
|
A function that relates the moles adsorbed with the amount of adsorbent present in the reaction medium.
|
A graph of the number of moles adsorbed as a function of temperature.
|
A physical adsorption model in which the formation of several layers on the surface of the adsorbent is taken into account.
|
Chemistry
|
An adsorption isotherm obtained assuming that only the first layer is coated on the adsorbent, that all its adsorption sites are equivalent, and that adsorption and desorption are non-cooperative processes.
| 175 | 3 |
c2e1a699-f9e4-447d-8285-5e16d34995f9
|
2020
|
In a mass spectrum, what is referred to as the base peak?
|
To the peak of the ion whose abundance is the smallest.
|
To the peak of the ion whose abundance is 0%.
|
To the peak of the ion whose abundance is 50%.
|
Chemistry
|
To the peak of the ion whose abundance is the greatest.
| 176 | 3 |
f014da83-59a3-473a-ab29-c52b9d42467c
|
2020
|
A technique widely used for protein separation is sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), in which sodium dodecyl sulfate (SDS) is used as a denaturing agent. In this technique, the proteins are separated:
|
Due to the difference in their isoelectric points.
|
Due to the difference in their molecular weight.
|
Due to the difference in their charge.
|
Chemistry
|
Due to the difference in their charge/radius ratio.
| 177 | 1 |
cba540bc-6bd9-4cb1-a7a0-bb8ba50f78fa
|
2020
|
The α helices of proteins are due to:
|
A random organization.
|
The formation of intramolecular hydrogen bonds between nearby residues.
|
To the absence of inter- or intramolecular hydrogen bridges.
|
Chemistry
|
The formation of intermolecular hydrogen bonds between neighboring residues.
| 178 | 1 |
1d4ce046-212e-4ffc-8f63-74d26656e4b4
|
2020
|
Which of the following biomolecules contains copper in the active center?:
|
Ascorbate oxidase.
|
Alcohol Dehydrogenase.
|
Vitamin B12.
|
Chemistry
|
Carbonic Anhydrase.
| 180 | 2 |
0599440e-0109-4ca8-a04e-0207ac7feb15
|
2020
|
Which of the following metal ions can be found in the active centers of superoxide dismutase enzymes?:
|
Mg2+.
|
Mn3+.
|
Co3+.
|
Chemistry
|
Cr3+.
| 181 | 1 |
36423899-40b6-4050-b041-ff2152e309b7
|
2020
|
Which of the following processes are catalyzed by Mn-catalase enzymes?:
|
2O2- + 2H+ → O2 + H2O2.
|
O2 + 4H+ + 4e- → 2H2O.
|
2H2O2 → 2H2O + O2.
|
Chemistry
|
2H2O → O2 + 4H+ + 4e-.
| 182 | 4 |
4ffaedcb-a459-42d0-a8cd-8352a9df6319
|
2020
|
If we ask for 96° alcohol in a pharmacy, they are selling us:
|
An azeotropic mixture of 96% alcohol and 4% water with a boiling point between the boiling point of water and the boiling point of alcohol.
|
Pure alcohol.
|
An azeotropic mixture of 96% alcohol and 4% water with a boiling point lower than the boiling point of water and the boiling point of alcohol.
|
Chemistry
|
Alcohol that has a boiling point of 96 °C.
| 183 | 4 |
f6033747-6dc7-4641-9812-8f79fc13d783
|
2020
|
The critical point of a pure substance:
|
It depends on the temperature at which it is determined.
|
It is the temperature that needs to be reached to liquefy a gas.
|
It is an invariant point of pressure and temperature for each substance.
|
Chemistry
|
It depends on the pressure at which it is determined.
| 184 | 4 |
eae01b91-e444-402f-9279-a8a7cc1e1bb3
|
2020
|
The mass balance of a saturated aqueous solution of the salt Ag3PO4 is:
|
[Ag+] = 3·([PO43-] + [HPO42-] + [H2PO4-] + [H3PO4])
|
3· [Ag+] = [PO43-] + [HPO42-] + [H2PO4-] + [H3PO4]
|
[Ag+] = [PO43-]3.
|
Chemistry
|
[Ag+] + [H+] = 3·([PO43-] + [HPO42-] + [H2PO4-]) + [OH-]
| 185 | 2 |
2d2974ec-ba73-4dc1-a103-5343f83f0ab3
|
2020
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.