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