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 |
|---|---|---|---|---|---|---|---|---|---|
Which of the following biological effects is produced by the action of insulin?: | Increase in glycolysis. | Increase in the degradation of glycogen. | Reduction of glucose uptake in the liver. | Chemistry | Reduction in the synthesis of fatty acids. | 25 | 2 | 6ae47db9-ffaf-49d3-87be-e293f4fb9b92 | 2024 |
Which of the following amino acids is synthesized from ribose 5-phosphate?: | Aspartate. | Histidine. | Proline. | Chemistry | Alanine. | 26 | 1 | 07f11305-aaf1-414f-8383-2af3c3fdeea8 | 2024 |
Which of the following lipoproteins contains apolipoprotein A1?: | HDL. | VLDL. | LDL. | Chemistry | IDL. | 27 | 2 | 81062876-7a75-457f-9f08-da6849e38e53 | 2024 |
Sphingomyelin is a sphingolipid formed by: | A ceramide and a fatty acid. | A ceramide and a phosphorylcholine group. | A sphingosine and a sugar. | Chemistry | A sphingosine and a fatty acid. | 28 | 1 | 8a8bcd6d-99f4-4960-9c65-a370d4025aef | 2024 |
What is the limiting step in the biosynthesis of fatty acids? | The condensation of an activated acyl group and two carbons derived from malonyl-CoA. | The formation of palmitate. | The reduction of the double bond to form the corresponding saturated acyl group. | Chemistry | The synthesis of malonyl-CoA in the reaction catalyzed by acetyl-CoA carboxylase. | 29 | 3 | e827e371-485b-4e57-8791-153ed743266f | 2024 |
The common precursor in the synthesis of adrenaline, noradrenaline and dopamine is: | Tryptophan. | Tyrosine. | Methionine. | Chemistry | Arginine. | 30 | 1 | 61e37c18-9cb7-49dd-8381-d99ec17d9d53 | 2024 |
The ATP is an example of: | Ribonucleoside. | Deoxyribonucleotide triphosphate. | Nucleic acid. | Chemistry | Ribonucleotide. | 31 | 3 | 4f4fcd4c-7432-48c0-ab1e-4e4a6541bd6b | 2024 |
Indicate the option that does not result in megaloblastic anemia: | Iron deficiency. | Cobalamin deficiency. | Lesch-Nyhan Syndrome. | Chemistry | Folic acid deficiency. | 32 | 2 | f9ac19b2-8d4d-4175-a15a-a7e28b3d5bd5 | 2024 |
In the metabolism of glycogen, indicate the incorrect answer: | Phosphorylase is regulated by allosteric interactions and by reversible phosphorylation. | The synthesis of glycogen requires the intervention of the enzyme phosphorylase. | Glycogen is composed of glucose units linked by α-1,4 glycosidic bonds and branches with α-1,6 glycosidic bonds. | Chemistry | Adrenaline and glucagon indicate the need to degrade glycogen. | 33 | 1 | fa228565-9584-4044-8158-2a58b884b676 | 2024 |
Which of the following enzymes catalyzes an irreversible reaction of gluconeogenesis?: | Phosphoglycerate kinase. | Glyceraldehyde 3-phosphate dehydrogenase. | Enolase. | Chemistry | Fructose 1,6-bisphosphatase. | 34 | 3 | 37e503b4-8c66-480f-820d-779643e3d4c8 | 2024 |
How does the binding of 2,3-bisphosphoglycerate (BPG) affect the affinity of hemoglobin for oxygen? | The affinity increases by binding to a site remote from the O2 binding site. | It reduces the affinity by binding to a site far from the O2 binding site. | Increases the affinity by binding to the O2 attachment site. | Chemistry | Reduce the affinity by binding to the O2 attachment site. | 35 | 1 | 631a9adf-4bb2-4d63-b5d4-62988bcc9df4 | 2024 |
Which of the following trace elements has no known function in the organism and can be a significant toxic agent?: | Selenium. | Molybdenum. | Chromium. | Chemistry | Aluminum. | 36 | 3 | b7868ff2-fc3f-49cd-b45a-082768dfe7f7 | 2024 |
The benchmark test to identify the presence of SARS-CoV-2 is the reverse transcriptase polymerase chain reaction (RT-qPCR). What parameter is evaluated to interpret a result as positive or negative? | The threshold value of the cycle number (Ct). | The time it takes to perform the RTqPCR. | The intensity of the fluorescent signal in the tenth amplification cycle. | Chemistry | The denaturation temperature of DNA strands. | 37 | 2 | 1365f6e3-858a-46ff-ba62-14b77330137b | 2024 |
Indicate which of the following pairs of "glucose transporter (GLUT) - main expression tissue" is correct: | GLUT3 - Muscle. | GLUT2 - Liver. | GLUT4 - Brain. | Chemistry | GLUT1 - Small intestine. | 38 | 1 | c9ffa4d5-d8bf-45cb-8122-2e86b1e81173 | 2024 |
Osmolarity is the measurement of the concentration of solutes defined as: | Number of osmoles of a solute per kilogram of solution (Osm/kg). | Number of osmoles of a solute per liter of solution (Osm/L). | Number of osmoles of a solute per milligram of solution (Osm/mg). | Chemistry | Number of osmoles of a solute per milliliter of solution (Osm/mL). | 39 | 1 | d67cd15f-e835-448a-97ab-46a9c99a8c58 | 2024 |
The disease of urine smelling like maple syrup is caused by a deficiency of: | Branched-chain α-keto acid dehydrogenase complex. | Phenylalanine hydroxylase. | Cystathionine β-synthase. | Chemistry | Arginase. | 40 | 2 | 10b3f577-89fc-4976-b8ed-9aa5a76c88b2 | 2024 |
Which statement is correct?: | Metallic elements usually form basic oxides; non-metallic elements usually form acidic oxides. | Metallic elements usually form acidic oxides; non-metallic elements usually form basic oxides. | The elements that form basic oxides tend to form volatile compounds. | Chemistry | The elements that form acidic oxides tend to form solid compounds. | 41 | 2 | 6f76fb10-b38e-4f77-938c-69d88854e35e | 2024 |
Which of the following statements about the elements of Group 15 of the Periodic Table is false?: | All members of the group, except N, are solids under normal conditions. | They exhibit a wide range of oxidation states. | Pentabromides are known for all members of the group, except for P. | Chemistry | Red phosphorus can be obtained by heating white phosphorus at 300ºC in an inert atmosphere for several days. | 42 | 4 | 170f6d30-a9dc-4702-957a-e1c494c092b0 | 2024 |
Which of the following hydroxides is not considered amphoteric?: | Aluminum hydroxide. | Beryllium hydroxide. | Magnesium hydroxide. | Chemistry | Zinc hydroxide. | 43 | 4 | 0e480ee5-d270-4d3f-98ee-5b33c376a51c | 2024 |
Cobalt-60, used in radiotherapy, can be produced by bombarding cobalt-59 with: | Beta particles. | Alpha particles. | Neutrons. | Chemistry | X-rays. | 44 | 4 | 205dc9a2-ccb7-4406-93b5-e0c2c3916076 | 2024 |
Which of the following statements about phosphorus trifluoride (PF3) is true?: | It is a weak σ-donor ligand and strong π-acceptor. | It is a strong σ-donor ligand and a strong π-acceptor. | It is a weak σ-donor and weak π-acceptor ligand. | Chemistry | It is a strong σ-donor ligand and weak π-acceptor. | 45 | 2 | 62fb7b59-73df-401f-a9ba-581a898134ba | 2024 |
Which substance is not considered a secondary pollutant in the urban pollution phenomenon known as "oxidizing" or photochemical smog? | Ozone. | Carbon monoxide. | Peroxyacetyl nitrate. | Chemistry | Nitrogen dioxide. | 46 | 1 | 8fb2efbb-a70b-4520-bf85-9a50a7b3a08f | 2024 |
Which statement in relation to the elements of Group 1 of the Periodic Table is true?: | Na reacts directly with oxygen to produce peroxide, Na2O2. | Rb reacts directly with oxygen to yield a simple oxide, Rb2O. | The K reacts at room temperature with nitrogen to form a nitride, K3N. | Chemistry | The K reacts directly with carbon to form a carbide, K2C2. | 47 | 2 | cd7abc8c-c3e9-4da7-877d-1e05e4f54ca5 | 2024 |
Which of the following statements about sulfur oxoanions is correct?: | The sulfite ion is a strong reducer, the sulfate ion is a strong oxidizer, and the persulfate ion is a strong reducer. | The sulfite ion is a strong oxidizer, the sulfate ion is a strong reducer, and the persulfate ion is minimally reactive. | The sulfite ion is a strong reductant, the sulfate ion is minimally reactive, and the persulfate ion is a strong oxidant. | Chemistry | The sulfite ion is slightly reactive, the sulfate ion is a strong oxidizer, and the persulfate ion is a strong oxidizer. | 48 | 4 | 22317c3b-7503-46f1-a263-afa4c02defdf | 2024 |
Regarding the advantages of using anionic clays as a complement to sunscreens, indicate the incorrect answer: | They promote close contact between the sunscreen and the skin, preventing allergies. | They stabilize the sunscreen. | They absorb UV-A ultraviolet radiation. | Chemistry | They absorb UV-B ultraviolet radiation. | 49 | 2 | 53039e91-4c82-46a7-be1a-4d31f89b23eb | 2024 |
Which of the following species is not considered a pseudohalide?: | Cyanate ion. | Cyanide ion. | Dicarbide ion. | Chemistry | Sulfocyanide ion. | 50 | 4 | 45a6d140-95a4-4159-82c9-75ef67dd4527 | 2024 |
If the Bohr radius of the first orbit of an atom is 0.5 Å. What is the radius of the second orbit? | 0.25 Å. | 0.125 Å. | 2.0 Å. | Chemistry | 1.0 Å. | 51 | 4 | 318d5ce1-817c-4ab6-8fbc-c8cbe11dc7d3 | 2024 |
Which of these molecules are isoelectronic with each other?: | Oxygen and ozone. | Nitrogen and carbon monoxide. | Water and sulfur dioxide. | Chemistry | Water and carbon dioxide. | 52 | 1 | c4f37d8f-2790-47e3-961d-d63c20770acf | 2024 |
What is the shape of the SO2 molecule? | Linear, with an O in the center. | Linear, with the S in the center. | Angular, with an O in the center. | Chemistry | Angular, with the S in the center. | 53 | 3 | 53b5f115-0e12-4534-beb8-01e76a68480e | 2024 |
What is the point group symmetry of the ammonia molecule? | C3v. | C2v. | Td. | Chemistry | D3h. | 54 | 2 | cf0c2a4c-90e1-41bd-ab1d-9e8ed8c041bf | 2024 |
Considering the unit cells of the cubic packing systems (EC), body-centered cubic (ECCC) and close-packed cubic (ECC), it can be said that they have, respectively: | 4, 5 and 10 atoms in the cell. | 8, 9 and 14 atoms in the cell. | 2, 3 and 8 atoms in the cell. | Chemistry | 1, 2 and 4 atoms in the cell. | 55 | 3 | 04c5dd79-dc1b-4b9e-9986-e342c7a723fb | 2024 |
The melting points of aluminum fluoride (1290°C) and aluminum iodide (190°C) are clearly different because: | The polarizability of iodide is greater than that of fluoride. | Aluminum has a low polarizability, and fluoride is much more polarizing than iodide. | The fluoride anion is very polarizing. | Chemistry | The aluminum fluoride is a covalent compound and the aluminum iodide is ionic. | 56 | 2 | 6a32428d-98c3-4a9f-a934-6c58358a62a1 | 2024 |
The molecule of Chlorine Trifluoride (ClF3): | It exhibits sp3 hybridization of its central atom. | It has F-Cl-F angles of 90°. | It has in the chlorine atom a single pair of unshared electrons. | Chemistry | It has all the Cl-F distances equal. | 57 | 3 | b2b580f1-3db6-4583-b83f-994cf2074578 | 2024 |
Unlike other elements, every metallic element is characterized by: | Its density and its high electrical and thermal conductivity. | Its shiny surface and its hardness. | The decrease in its electrical conductivity as the temperature increases. | Chemistry | The increase in its electrical conductivity as the temperature rises. | 58 | 4 | dcfff8b0-b2c7-48d6-a161-72eb671c2f0e | 2024 |
To which of the following symmetry groups can a polar molecule belong?: | Oh. | Dꝏh. | Cꝏv. | Chemistry | Sci. | 59 | 4 | 9d40b40f-95ef-4f2e-ae3e-e97dddab852e | 2024 |
Indicate which of the following statements is true if the reduction potential of the perchlorate ion to chlorate ion is 1.20 V in acidic medium and 0.37 V in basic medium: | The oxidizing capacity of the perchlorate ion decreases as the pH increases. | The perchlorate ion is a better reducing agent in an acidic medium than in a basic medium. | The perchlorate ion is reduced more easily in a basic medium than in an acidic medium. | Chemistry | The oxidizing capacity of the perchlorate ion increases as the pH increases. | 60 | 2 | 3e32d6d0-eb43-4728-aa87-333d6aaa6c17 | 2024 |
The Tc is a widely used isotope in medicine that is obtained by the decay, with the emission of a beta particle (β–), of the isotope: | Mo (Molybdenum) | Tc. | Ru. | Chemistry | Mo. | 61 | 3 | c3393128-76a0-4b15-a14f-0449b691d644 | 2024 |
Which of the following statements about Frenkel defects is true?: | They are a type of intrinsic defect. | They are a type of extrinsic defect. | Its presence in a compound alters the electrical neutrality of it. | Chemistry | Its presence in a compound alters its stoichiometry. | 62 | 2 | e3b96f59-9481-4ec5-8c98-b1ad7926e1a4 | 2024 |
Among the compounds most commonly used as contrast agents in magnetic resonance imaging (MRI) are the coordination compounds of: | Gadolinium. | Strontium. | Lead. | Chemistry | Francium. | 63 | 2 | 5108a4e1-8e58-4f41-bf98-22644367411a | 2024 |
How many Fe-Fe bonds should the compound Fe2(CO)9 have in order to comply with the 18 valence electron rule? | One. | None. | Three. | Chemistry | Two. | 64 | 2 | 767b2e25-9c85-4f1a-9823-33cc34e04e10 | 2024 |
On chromium compounds: | Potassium dichromate in the presence of concentrated hydrochloric acid generates potassium chromate. | Chromium is easily attacked by air, so steel is used to coat it and thus protect it. | Cr(VI) compounds are carcinogenic. | Chemistry | The high stability of potassium dichromate means that it is not an oxidizing agent. | 65 | 4 | 030b3e72-3b93-44ae-8d2d-e251a06941b3 | 2024 |
It is true that: | Hydrofluoric acid is a stronger acid than hydrochloric acid. | Potassium chlorate is a weak oxidizing agent. | Hydrofluoric acid is stored in glass bottles, as it attacks plastic. | Chemistry | Hypochlorous acid is a stronger oxidant than sodium hypochlorite. | 66 | 3 | 811094d8-7a05-403f-bca2-bf2ec5f55f9a | 2024 |
Indicate the correct answer regarding hydrogen: | It is very reactive at room temperature, due to the weakness of the H-H bond. | It is the most abundant element in the Universe and very abundant in the Earth's atmosphere in the form of H2. | The idea of using it as fuel instead of fossil fuels is known as "Water Economy." | Chemistry | It is used in the saturation of unsaturated fats in the presence of catalysts such as palladium. | 67 | 3 | 3628e346-d3b6-479a-8171-bf3198e60d46 | 2024 |
Hydrogen peroxide: | It easily disproportionates in the presence of traces of alkali. | It is a solid at room temperature. | Reduce the salts of Fe(III) to Fe(II) in an acidic medium. | Chemistry | It is a stronger base than water. | 68 | 2 | e8d785d6-4943-4329-863f-a68386e23b67 | 2024 |
Two isomers of the compound [M(Cl)2(NH3)2] are known, while only one is known of the compound [M(Br)2(Cl)2]. What is the justification for this fact? | [M(Cl)2(NH3)2] is tetrahedral and [M(Br)2(Cl)2] is square planar. | [M(Cl)2(NH3)2] is square planar and [M(Br)2(Cl)2] is tetrahedral. | Both compounds are square planar, but in [M(Cl)2(NH3)2] the ligands are in trans and in [M(Br)2(Cl)2] the ligands are in cis. | Chemistry | Both compounds are square planar, but in [M(Cl)2(NH3)2] the ligands are in cis and in [M(Br)2(Cl)2] the ligands are in trans. | 69 | 1 | 2ec4a114-c901-459d-96d5-d28001589050 | 2024 |
The most stable allotrope form of elemental sulfur is formed by: | Sulfur atoms forming branched zigzag chains. | Sulfur atoms forming linear zigzag chains. | Eight sulfur atoms joined together forming a zigzag ring. | Chemistry | Six sulfur atoms joined together forming a zigzag ring. | 70 | 4 | 74a4b2ca-b086-45c0-ad6a-9a488e3e2816 | 2024 |
What is the space occupancy efficiency in a face-centered cubic packing? | 68% | 52% | 91% | Chemistry | 74% | 71 | 3 | 1e96e951-d155-4fd9-a7e0-3b0a6fb60aa8 | 2024 |
The ammonium cation is often considered a pseudo-alkali metal. Which of the following reasons is false?: | Because, just like with alkali metals, their salts are mostly colorless and soluble in water. | Because it has a +1 charge like all alkali metals. | Because, despite containing two non-metals, its size falls within the range of sizes of the alkali cations. | Chemistry | Because the chemical reactions that its nitrate undergoes are the same as those of the nitrates of alkali metals. | 72 | 3 | 5a44bdce-5b5f-4f8c-9da8-9bd2975ff09d | 2024 |
How is the trans- [Pt(Cl)2(NH3)2] compound synthesized? | Starting from [Pt(NH3)4]2+ making it react with 2 equivalents of HCl. | Starting from [Pt(Cl)4]2‒ making it react with 2 equivalents of NH3. | Starting from [Pt(NH3)4], making it react with 2 equivalents of HCl. | Chemistry | Starting from [Pt(Cl)4]4+, making it react with 2 equivalents of NH3. | 73 | 2 | c07ef360-3662-40b5-8edf-e8c78b60024d | 2024 |
Indicate the false answer regarding the hardness of water: | It is due to the presence of Mg2+ and/or Ca2+ ions in solution. | It can be temporary or permanent. | The presence of polyphosphates in the medium does not affect the hardness of the water. | Chemistry | It causes insoluble foams when reacting with the stearate ions of soaps. | 74 | 4 | 8ececf60-5536-4d59-9f34-853a0c0a168a | 2024 |
Which statement is correct about carbonyl, sulfo, and triphenylphosphine ligands?: | Carbonyl is a strong field, sulfo is a strong field and triphenylphosphine is a weak field. | Carbonyl is a weak field, sulfur is a strong field, and triphenylphosphine is a weak field. | Carbonyl is a strong field, sulfo is a weak field, and triphenylphosphine is a weak field. | Chemistry | Carbonyl is of strong field, sulfo is of weak field and triphenylphosphine is of strong field. | 75 | 3 | 0058b1cd-2b6a-4447-9fd8-0aaefeaba482 | 2024 |
What is the only existing term for a p1 configuration? | 1P. | 1S. | 1D. | Chemistry | 2P. | 76 | 3 | 7ac1f3ac-e775-4ea6-ac8f-d237d22c6c55 | 2024 |
Silicon doped with arsenic is: | An intrinsic semiconductor. | An insulator. | An extrinsic n-type semiconductor. | Chemistry | A p-type extrinsic semiconductor. | 77 | 4 | 79254b34-e3f1-450f-a297-d590c54214df | 2024 |
The boiling point of hydrogen halides follows the order: | HF >> HCl < HBr < HI. | HF >> HCl > HBr > HI. | HF << HCl < HBr < HI. | Chemistry | HF = HCl > HBr < HI. | 78 | 2 | 57705951-170c-4e5a-8940-bc3b57863728 | 2024 |
With which organic fragment is the organometallic fragment Fe(CO)4 isolobal? | CH2. | CH. | CH4. | Chemistry | CH3. | 79 | 2 | 28d3665d-73b9-4cd7-a2e7-3f21084e9fb0 | 2024 |
Osmium tetroxide reacts with alkenes to produce: | Anti neighboring diols. | Syn neighboring diols. | Racemic mixture of oxacyclopropane derivatives. | Chemistry | Equimolar mixture of vicinal diols in a sin:anti ratio. | 80 | 1 | ce0f9ac1-379e-45b6-83d2-aedc129b389b | 2024 |
Which of the following reagents is used in the reductive amination reaction of carbonyl compounds and organic amines?: | Sodium borohydride. | m-Chloroperbenzoic Acid. | Copper (I) and ascorbic acid. | Chemistry | Sodium cyanoborohydride. | 81 | 3 | f76c1c1b-4122-4b97-8609-9e434c786bc8 | 2024 |
The SN1 substitution of (2R,4R)-2-bromo-4-methylhexane with ethanol in an acidic medium produces: | (2S,4R)-2-Ethoxy-4-methylhexane. | (2rac,4R)-2-Ethoxy-4-methylhexane. | (2R,4R)-2-Ethoxy-4-methylhexane. | Chemistry | (2R,4rac)-2-Ethoxy-4-methylhexane. | 82 | 1 | 3e32f3bc-748f-4f5c-8745-c66edaca8b9a | 2024 |
The condensation of carbonyl compounds with secondary amines leads to the formation of the corresponding enamines. What is the main advantage of the reaction of these enamines with haloalkanes? | Regioselective formation of aziridinic derivatives. | Insertion of halogens in the alpha position to the carbonyl group. | Minimization of multiple alkylation at the alpha position of the carbonyl derivative. | Chemistry | Formation of alpha-beta hydroxyamines. | 83 | 4 | 57fa6203-3d51-4bc8-b701-ae81ef1c2cf0 | 2024 |
Which of the following is the best leaving group in an SN2 substitution reaction?: | Cl–. | I-. | F-. | Chemistry | Br-. | 84 | 1 | a8b72e2c-c5bc-478b-871e-f21351c0d4e4 | 2024 |
What product would be predominantly obtained when treating (S)-2-bromobutane with sodium ethoxide in ethanol? | 1-butene. | (R)-2-ethoxybutane. | Racemic 2-ethoxybutane. | Chemistry | 2-butene. | 85 | 3 | c73cc671-7b07-4eb9-911a-e75ce63d6936 | 2024 |
What product is formed when ethyl pentanoate reacts with two equivalents of ethylmagnesium bromide? | 3-hexanone. | 3-heptanone. | 3-ethyl-3-heptanol. | Chemistry | 3-methyl-3-heptanol. | 86 | 4 | 19a7361c-4cf5-4792-957d-fa0ae88e81a9 | 2024 |
What product will be formed when 2-phenylpropanal reacts with the following compound? | 5-phenyl-3-penten-2-one. | 4-phenyl-2-pentenal. | 5-phenyl-2-hexanone. | Chemistry | 5-phenyl-3-hexen-2-one. | 87 | 3 | 73532abd-692a-496b-8aaf-c85ab8c5ac5a | 2024 |
Which of the following organic liquids is denser than water?: | Toluene. | Tetrahydrofuran. | 2-chloro-2-methylpropane. | Chemistry | Dichloromethane. | 88 | 3 | ef89291c-3a3b-4191-9067-83e0ad201119 | 2024 |
Which of the following cyclic systems is antiaromatic, according to Hückel's rule? | Cyclopentadienyl cation. | Cycloheptatrienyl cation. | Cyclooctatetraenyl dianion. | Chemistry | Cyclopentadienyl anion. | 89 | 2 | 2f9e5c7c-21ee-44fd-87c6-b399e61fd24b | 2024 |
Which of the following statements about polymers is false?: | The polyglycolic and polylactic acids are biodegradable polyesters. | Neoprene is a synthetic rubber produced from 2-chloro-1,3-butadiene. | The Ziegler-Natta catalyst allows the production of low-density polyethylene, which is very resistant. | Chemistry | Vulcanized rubber has a hardness and elasticity much greater than natural rubber. | 90 | 4 | b8d5d8b6-2721-4a80-8f49-8552b95487ea | 2024 |
Which of the following statements about sugars is false?: | The Wohl degradation of D-glucose produces D-arabinose. | The D-idose and the D-gulose are epimers at C-2 and, therefore, form the same osazone. | The reduction of D-galactose with sodium borohydride produces sorbitol, a polyalcohol used as a food additive. | Chemistry | When D-allose is treated with nitric acid, an optically inactive aldonic acid is produced. | 91 | 4 | ab2e0178-0cf7-430c-a118-1f67487b4e0d | 2024 |
Which of the following statements is correct?: | Oleic acid is a polyunsaturated fatty acid. | Waxes and glycerides are simple, non-hydrolyzable lipids. | A soap is a sodium or potassium salt of glycerol. | Chemistry | Biodiesel is a mixture of fatty acid methyl esters. | 92 | 3 | d200fb37-6987-48ee-bd2e-15f5b5c73f61 | 2024 |
What is the majority organic product obtained in the reaction of 2-methylpropanal with sodium hydroxide? | 2-Methylpropanoic Acid. | 2-Methylpropanol. | 2,3,4-Trimethylpentanal. | Chemistry | 3-Hydroxy-2,3,4-trimethylpentanal. | 93 | 3 | 24a38303-73a2-40b3-802b-cd9c04cd38a1 | 2024 |
What predominant type of organic compound would you expect in the reaction of cyclohexanone with methylamine in the presence of sodium cyanoborohydride in ethanol? | A hydroxylamine. | A nitrile. | An imine. | Chemistry | An amine. | 94 | 3 | 91010a14-bebc-4901-ac2d-ca801ae23f14 | 2024 |
What reaction conditions could convert an aniline into a phenol? | Treatment with sodium hydroxide, followed by heating in water. | Treatment with sodium nitrite in an acidic medium, followed by heating in water. | Treatment with hydrogen chloride, followed by heating in water. | Chemistry | Treatment with thionyl chloride in an acidic medium, followed by heating in water. | 95 | 1 | c04204c1-d271-4bde-bc51-7547813e0b24 | 2024 |
What is the main organic product obtained in the reaction of hexanoic acid with lithium aluminium hydride, after an acid work-up? | Hexanal. | Hexanol. | Hexane. | Chemistry | Lithium hexanoate. | 96 | 1 | edac2c8a-2f90-4abe-80b4-7f94db107bc1 | 2024 |
What is the synthesis of quinolines known as, which involves heating aniline with glycerol, concentrated sulfuric acid, nitrobenzene, and ferrous sulfate? | Combes Synthesis. | Friedländer Synthesis. | Skraup Synthesis. | Chemistry | Doebner Synthesis. | 97 | 4 | 04772d0a-bfb8-4c0e-a4d6-477cd7dc87ad | 2024 |
Thiophene is an aromatic compound with a sulfur in a ring of: | Four links. | Three links. | Six links. | Chemistry | Five links. | 98 | 3 | e03f8226-d6e8-4687-a70c-21b6d108f82d | 2024 |
What compound results from the addition of HBr to 1-butene in the presence of peroxides? | CH3CH2CH2CH2Br. | CH3CH2CHBrCH3. | CH2BrCH2CH=CH2. | Chemistry | CH3CHBrCH=CH2. | 99 | 2 | f79140f3-818e-4809-a260-2e6a261f2c91 | 2024 |
What chemical reaction is used to transform an alkyne into a ketone? | Hydroboration. | Hydrogenation with Lindlar catalyst. | Hydration under catalysis by acid and mercuric ion. | Chemistry | Reaction with Grignard reagents. | 101 | 4 | ebfef547-ec0b-48eb-9624-fc73ac66f955 | 2024 |
What is the decreasing order of reactivity of the following compounds towards electrophilic aromatic substitution?: | Phenol > Benzoic Acid > Toluene > Benzene. | Phenol > Toluene > Benzene > Benzoic Acid. | Benzoic Acid > Toluene > Benzene > Phenol. | Chemistry | Toluene > Benzene > Phenol > Benzoic Acid. | 104 | 1 | 9686fbee-dbd1-4e4c-9b4b-545573ee87ad | 2024 |
What is the best sequence of reactions to prepare heptan-2-one? | a) acetylene, NaNH2; b) 1-bromopentane; c) H2O, HgSO4, H2SO4. | a) propyne, NaNH2; b) 1-bromobutane; c) H2O, HgSO4, H2SO4. | a) acetylene, NaNH2; b) bromomethane; c) NaNH2; d) 1-bromobutane; e) H2O, HgSO4, H2SO4. | Chemistry | a) hex-1-yne, NaNH2; b) bromomethane; c) H2O, HgSO4, H2SO4. | 105 | 2 | 15aefc81-1dbd-4694-a771-de28a35773bd | 2024 |
The reaction of a phosphorus ylide on a carbonyl group allows us to obtain: | An alcohol. | A condensation aldol dimer. | An aldol. | Chemistry | An alkene. | 106 | 3 | a3445c32-c34a-4f01-b9b8-9bfcc7a131a5 | 2024 |
Regarding the acidity of the following compounds: benzoic acid, p-methoxybenzoic acid, and p-nitrobenzoic acid, it is established that: | The least acidic is the p-methoxybenzoic acid and the most acidic is the p-nitrobenzoic acid. | The least acidic is benzoic acid and the most acidic is p-methoxybenzoic acid. | The least acidic is benzoic acid and the most acidic is p-nitrobenzoic acid. | Chemistry | The least acidic is the p-methoxybenzoic acid and the most acidic is benzoic acid. | 107 | 2 | c33b020a-0053-4a8f-b1c1-16db0f4a545f | 2024 |
Treatment with Na, NH3(liquid) on 2-octyne leads to: | Octane. | (E)-2-octene. | (Z)-2-octene. | Chemistry | 1,2-octadiene. | 108 | 1 | c016b6f6-8838-469b-85bc-b52d25ec0687 | 2024 |
What is the solvent of choice if the reaction of 1-iodo-pentane with sodium azide (NaN3) is intended to proceed with the most favorable kinetics? | Water. | Propanol. | Acetic acid. | Chemistry | Dimethylformamide. | 109 | 3 | 157e7f48-c422-4eb9-a8c4-e494eda94622 | 2024 |
Which of the nuclei indicated cannot be analyzed by a Nuclear Magnetic Resonance spectrometer? | A nucleus with an odd number of protons and an even number of neutrons. | A nucleus with an odd number of protons and an odd number of neutrons. | A nucleus with an even number of protons and an even number of neutrons. 1) BH3/THF 2) H2O2/OHPCC CH2Cl2 1) CH3MgBr 2) H3O+ | Chemistry | A nucleus with an even number of protons and an odd number of neutrons. | 111 | 4 | 5841823a-b028-450e-8d03-479c15d64d17 | 2024 |
What is the most appropriate method to prepare n-butylbenzene from benzene? | CH3CH2CH=CH2 / H2SO4. | CH3CH2CH2CH2Cl / AlCl3. | a) CH3CH2CH2COCl / AlCl3; b) H2NNH2 / KOH, heat. | Chemistry | CH3CH2CH2CH2OH / H2SO4. | 113 | 4 | acbe3293-1c20-42b5-8818-9ef5128c99ca | 2024 |
The treatment of acetophenone (Ph-CO-CH3) with Br2/CH3COOH leads to: | It does not react under these conditions. | Mixtures of o-BrPh-CO-CH3 + p-BrPh-COCH3. | Ph-CO-CH2Br. | Chemistry | m-BrPh-CO-CH3. | 115 | 4 | f7ba2c1e-d665-4f75-bc4c-63824bd6716f | 2024 |
Under what reaction conditions would an alcohol be obtained with anti-Markovnikov regioselectivity from an alkene? | Epoxidation using a peroxycarboxylic acid followed by hydrolysis. | Hydroboration followed by oxidation. | Palladium acetate, CuCl2 in water. | Chemistry | Hydration in strong acid medium. | 117 | 1 | a4b8ecd1-e33a-4629-a354-982cfc55e8bd | 2024 |
The Chichibabin reaction involves the condensation of aldehydes and ammonia to obtain: | Pyridines. | Indoles. | Pyrrolidines. | Chemistry | Triazoles. | 118 | 2 | cddafaf1-a7d0-4f53-9453-5a500702cd6d | 2024 |
Which of the indicated ketones is suitable as a starting product for the haloform reaction to take place? | 2-Pentanone. | 3-Heptanone. | Cyclohexanone. | Chemistry | 2-Methyl-3-hexanone. | 119 | 2 | 2a86f917-84ef-4e23-863e-a472d78a92ec | 2024 |
A chromatogram is: | A graph that represents the separation of an analyte from its matrix as a function of mass versus elution volume. | A graph of some function of the solute concentration versus time or elution volume. | A graph that relates the intensity of an analyte signal in the detector to the concentration. | Chemistry | A three-dimensional graph representing a function of the concentration and elution volume against the density. | 120 | 1 | 48ff8a95-c506-4323-b147-330c4778dce1 | 2024 |
What is the ionic strength of a solution formed by KNO3 0.05 M and Na2SO4 0.1 M? | 0.25 M. | 0.55 M. | 0.35 M. | Chemistry | 0.15 M. | 121 | 4 | 165c6aec-1300-4643-93e6-775344c1bfa9 | 2024 |
In a chromatogram for a mixture of two components, it is observed that the peaks are not well resolved. Assuming that the length of the column is set at 25 cm and that the packing material is fixed, what measures could be taken to increase the resolution? | Resolution is not a parameter that can be increased or decreased because it does not depend on the chemical nature of the compounds. | Change the eluent, add a buffer to the aqueous phase, or vary the temperature. | Optimize the composition of the mobile phase so that the selectivity factor (α) of the solutes is equal to 1. | Chemistry | Increase the chromatogram time and decrease the inflow rate to the column. | 122 | 1 | 92cf90a8-0310-4ee9-92fb-fdddb30c87ff | 2024 |
Which of the following is not a type of metallic indicator electrode?: | Of the first kind. | Membrane-based. | Redox. | Chemistry | Of the third kind. | 123 | 1 | 2efd51cc-452b-49e1-af9f-3fe479de8115 | 2024 |
In atomic absorption spectrometry, cold vapor atomization is applied in the quantification of: | Mercury. | Iron. | Lead. | Chemistry | Nickel. | 124 | 2 | 09b4b414-1457-484e-8469-ce8b05b7ba5d | 2024 |
Indicate the correct answer regarding the following detectors used in gas chromatography: | The flame ionization detector (FID) causes carbonyl, alcohol, halogen, and amine functional groups to generate many ions in the flame. | The thermal conductivity detector (TCD) has a wide range of applications since it is very sensitive. | The electron capture detector (ECD) is widely used in environmental samples as it is sensitive to halogenated organic compounds such as polychlorinated biphenyls. | Chemistry | The thermionic detector is sensitive to organic compounds that contain sulfur and halogens. | 125 | 4 | 1ac07112-cb77-42ea-af0c-081bdce7609d | 2024 |
Which solvent has a greater elution strength in silica adsorption chromatography? | Pentane. | Hexane. | Acetonitrile. | Chemistry | Methanol. | 126 | 3 | bb209ae5-f3a2-4147-9f47-37b8c656d9f0 | 2024 |
What is the CORRECT option in relation to chemical ionization in mass spectrometry?: | It produces more fragmentation than electronic ionization. | Does not provide molecular peak. | Increases the ability to separate two peaks of similar masses. | Chemistry | The ionization source is filled with a reactive gas. | 127 | 3 | 7c17e450-c7d5-4d97-8e22-4f4d34139484 | 2024 |
Dialysis is a separation technique that is based on: | The pressure difference that is established on both sides of the dialysis membrane. | The molecular size of the different analytes present in the sample. | The difference between the ionic forces of the sample and the capturing agent or solvent. | Chemistry | The different affinities of the analytes to the solvent or capturing agent. | 128 | 1 | 8fc348a9-2b84-44a6-845c-68af9d547771 | 2024 |
If the amino acids in a blood plasma sample are quantified using cation exchange HPLC, which of the following elutes last?: | Aspartic acid. | Phenylalanine. | Threonine. | Chemistry | Arginine. | 129 | 3 | 15b8363e-995c-454d-8749-c8ec08329df7 | 2024 |
Which of the following is not a method for the determination of total proteins in human serum?: | Kjeldahl. | Biuret. | Winkler. | Chemistry | Lowry. | 130 | 4 | 008a0b93-8517-4e3f-90bf-73b4bb6aef92 | 2024 |
As a consequence of electroosmotic flow, the elution order in a characteristic capillary electrophoresis separation, being: A = anions with greater electrophoretic velocity (v), B = anions with lesser v, C = neutral species, D = cations with greater v, and E = cations with lesser v, is: | D, E, C, B, A. | A, B, C, D, E. | D, E, A, B, C. | Chemistry | A, B, E, D, C. | 131 | 2 | ed9678ea-6a53-47f0-8bb9-9c4cd95b1eb5 | 2024 |
Subsets and Splits
No saved queries yet
Save your SQL queries to embed, download, and access them later. Queries will appear here once saved.