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Nitriles are hydrolyzed to:
|
Amines.
|
Aldehydes.
|
Carboxylic acids.
|
Chemistry
|
Ketones.
| 127 | 4 |
0aad6acb-9e01-4237-a6ba-fffadfd13352
|
2023
|
The structure of furan is analogous to that of pyrrole, except that the NH has been replaced by an:
|
C.
|
S.
|
P.
|
Chemistry
|
O.
| 128 | 3 |
2396dc79-51ba-405b-bc53-3ee943fe33c4
|
2023
|
The fusion of a benzene ring in positions 2,3 of a pyrrole generates:
|
Isoquinoline.
|
Quinoline.
|
Indole.
|
Chemistry
|
Quinidine.
| 129 | 4 |
67dd48b4-4f22-4994-b805-a0a63bdd9a94
|
2023
|
Indicate which of the following cations is more stable:
|
CH3–CH2+.
|
CH3+.
|
CH2=CH–CH2+.
|
Chemistry
|
(CH3)2CH+.
| 131 | 4 |
197367ab-df10-4ac3-8162-351c3f1dac11
|
2023
|
What product/s will result from treating (E)-3-hexene with Br2?
|
A mixture of diastereomeric dibromides.
|
A mixture of enantiomeric dibromides.
|
A meso dibromide.
|
Chemistry
|
(E)-3,4-dibromo-3-hexene.
| 134 | 4 |
32444e22-5446-4734-9f6b-2cc8b90f44d7
|
2023
|
Which of the following statements, about the heterocycle pyridine, is false?:
|
The reaction of pyridine with acetic acid yields pyridinium acetate.
|
Pyridine is a stronger base than pyrrole.
|
Pyridine is a stronger base than piperidine.
|
Chemistry
|
Pyridine is deactivated towards electrophilic attack, but it is activated towards aromatic nucleophilic substitution.
| 135 | 4 |
dce68f04-38bb-4007-b14c-de888a78f109
|
2023
|
What is the name of the reaction by which, in the presence of a strong base, primary amides react with chlorine or bromine to form amines with one less carbon atom?
|
Curtius Rearrangement.
|
Gabriel Synthesis.
|
Sandmeyer Reaction.
|
Chemistry
|
Hofmann Rearrangement.
| 136 | 3 |
0af52935-336f-4560-88e6-5f3db90e228b
|
2023
|
The 2-butanol can be obtained from propyne through the following sequence of reactions:
|
1. NaOH; 2. CH3Br; 3. H2/cat. Lindlar; 4. H+/H2O.
|
1. NaNH2; 2. CH3Br; 3. H2/cat. Lindlar; 4. H+/H2O.
|
1. NaNH2 ; 2. CH3CH2Br ; 3. H2/cat. Lindlar ;4. H+/H2O.
|
Chemistry
|
1. NaNH2 ; 2. CH3Br ; 3. H2/Pd-C; 4. H+/H2O.
| 137 | 1 |
c485f13b-79f7-40f4-9659-8d399643ca7f
|
2023
|
What is the major product obtained when ethyl acetoacetate is treated with an excess of sodium borohydride in methanol?
|
1,3-butanediol.
|
Methyl 3-hydroxybutanoate.
|
4-hydroxy-2-butanone.
|
Chemistry
|
3-oxobutanoic acid.
| 139 | 1 |
6d47f992-f551-4613-a21e-f0d932f8f177
|
2023
|
Which of the following statements is true?:
|
Grignard reagents are electrophilic reagents in their reaction with ketones.
|
The reaction between a ketone and a Grignard reagent is irreversible because carbocations are poor leaving groups.
|
The reaction between a ketone and a Grignard reagent is irreversible because carbanions are poor leaving groups.
|
Chemistry
|
Ketones are nucleophilic reagents in their reaction with Grignard reagents.
| 141 | 4 |
3dfaa177-bb92-4ba0-bbac-1f3c21dc027d
|
2023
|
Which of the following bases is most suitable for carrying out the transformation of 2-bromo-3-methylbutane into 2-methyl-2-butene?:
|
Pyridine.
|
KOCH3.
|
Lithium diisopropylamide.
|
Chemistry
|
KOC(CH3)3.
| 143 | 1 |
ac51ded8-e3a0-46c9-8404-800c66391dc3
|
2023
|
What is the descending order of nucleophilicity, in hydroxylic solvents, of the following species: water, methoxide ion, triethylphosphine, and acetate ion?
|
Triethylphosphine > methoxide ion > acetate ion > water.
|
Methoxide ion > acetate ion > triethylphosphine > water.
|
Acetate ion > methoxide ion > triethylphosphine > water.
|
Chemistry
|
Triethylphosphine > acetate ion > methoxide ion > water.
| 144 | 2 |
785d57dd-1a1c-418c-b513-9b69009bdc4a
|
2023
|
Which of the following statements about tautomerism is false?:
|
Tautomers are resonant forms.
|
Tautomers are isomers that interconvert.
|
Tautomerism occurs due to the migration of a proton and the movement of a double bond.
|
Chemistry
|
Tautomers are different compounds.
| 146 | 2 |
d99133cd-6111-436f-a73d-6b2f65a04a4b
|
2023
|
What is the majority organic product obtained in the reaction of 2-methylpropanal with sodium hydroxide at 5ºC?
|
2-methylpropanoic acid.
|
2-methylpropanol.
|
2,3,4-trimethylpentanal.
|
Chemistry
|
3-hydroxy-2,3,4-trimethylpentanal.
| 147 | 3 |
4dc7e870-2127-4229-b09b-330239c6f3fa
|
2023
|
Which of the following statements is false?:
|
The metathesis reaction with ring opening of cyclic alkenes is usually carried out with Grubbs' reagent.
|
The metathesis reaction with ring opening of cyclic alkenes gives rise to dienes.
|
The ring-opening metathesis reaction of cyclic alkenes can be carried out in the presence of other functional groups.
|
Chemistry
|
The metathesis reaction with ring opening of cyclic alkenes leads to the formation of ethylene.
| 149 | 3 |
a25822d8-ff7b-4efe-bc35-460747a06ee8
|
2023
|
Which of the following techniques is not suitable for separating the enantiomers of a racemic mixture of thalidomide?:
|
Distillation.
|
Chiral chromatography.
|
Reaction with chiral resolution agents.
|
Chemistry
|
Crystallization.
| 150 | 2 |
9f328290-13c5-41f1-8561-44bda0c290c0
|
2023
|
The general formula of an acyclic hydrocarbon with two triple bonds is:
|
CnH2n–6.
|
CnH2n-4.
|
CnH2n–10.
|
Chemistry
|
CnH2n-2.
| 151 | 2 |
fb45ea2c-a428-4d6f-99fd-62c1fa8b7b52
|
2023
|
What is the phrase that best describes the mechanism of nucleophilic substitution in a tertiary halide?:
|
Concerted reaction with retention of configuration.
|
Formation of a carbocation with retention of configuration.
|
Formation of a carbocation with partial racemization.
|
Chemistry
|
Concerted reaction with inversion of configuration.
| 152 | 4 |
0df8ab35-23a0-4583-a731-403194733504
|
2023
|
What product would be obtained by treating 2,3-dimethyl-2,3-butanediol with H2SO4, at 100ºC?
|
2,3-dimethyl-1,3-butadiene.
|
3,3-dimethyl-2-butanone.
|
Acetone (2 equivalents).
|
Chemistry
|
1,1,2,2-tetramethyloxirane.
| 153 | 1 |
ec986a84-7a4f-430a-964d-d800e8e7b007
|
2023
|
What product is obtained by heating 1,3-butadiene with acrylonitrile (CH2=CH–C≡N)?
|
3-cyclohexene-1-carbonitrile.
|
4-vinylcyclohex-1-ene.
|
6-vinyl-2,5-dihydropyridine.
|
Chemistry
|
3-vinylcyclobutane-1-carbonitrile.
| 154 | 2 |
4e0e60c1-32f2-402e-890b-ac41ddfb4d55
|
2023
|
Which of the following pi cyclic systems is aromatic?:
|
Cyclopropenyl cation.
|
Cyclooctatetraene.
|
Cyclopentadienyl cation.
|
Chemistry
|
Cyclopropenyl anion.
| 155 | 2 |
d856d0df-5f72-4f46-8a1e-9dec95afa23d
|
2023
|
What type of predominant 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.
| 156 | 3 |
5a3bb4b4-7a68-4490-aac8-8498fd90910c
|
2023
|
The compound (R,R)-1,2-dibromocyclobutane:
|
It is an optically inactive compound.
|
It has two asymmetric carbons and is therefore a chiral compound.
|
It has no asymmetric carbons and is therefore an achiral compound.
|
Chemistry
|
It is a meso compound and therefore an achiral compound.
| 157 | 1 |
591e7e2f-fcee-47a8-9fcb-36843c95544f
|
2023
|
In the reaction of cis- and trans-1-bromo-4-(1,1- dimethylethyl)cyclohexane with sodium methoxide:
|
A mixture of cis- and trans-4-(1,1-dimethylethyl)-1-methoxycyclohexane is produced.
|
Trans-4-(1,1-dimethylethyl)-1-methoxycyclohexane is produced.
|
4-(1,1-dimethylethyl)cyclohex-1-ene is produced, the reaction being faster if starting from the cis isomer of the starting substance.
|
Chemistry
|
The compound 4-(1,1-dimethylethyl)cyclohex-1-ene is produced, with the reaction being quicker if starting from the trans isomer of the starting substance.
| 158 | 4 |
89293250-c460-45bf-b440-977c023465ec
|
2023
|
Which of the following statements, related to acetals, is false?:
|
Aldehydes form acetals faster than ketones.
|
The formation of acetals is catalyzed only by acids, but hydrolysis requires basic conditions.
|
Ethylene glycol is often used to prepare cyclic acetals.
|
Chemistry
|
The formation of an acetal does not alter the oxidation state of the carbon atom of the precursor carbonyl group.
| 159 | 1 |
f57ee15c-dd9e-42f7-be46-1c82dd9eabf5
|
2023
|
Which of the following statements is correct for glycosphingolipids?:
|
Its main function is energy storage.
|
They are nonpolar.
|
They have two fatty acid residues in their molecule.
|
Chemistry
|
In the event they carry sialic acid, they are called gangliosides.
| 160 | 3 |
d4dd0f35-754c-48c4-81c6-6482103644de
|
2023
|
Which of the following statements is true for the oxidation of fatty acids?:
|
It takes place in the cytosol.
|
The oxidation and synthesis of fatty acids occur with the same reactions, but in the opposite direction.
|
Fatty acids must be activated (by binding to CoA) to allow their internalization into the mitochondria.
|
Chemistry
|
It occurs with low plasma levels of glucagon or adrenaline.
| 161 | 4 |
e15d6c72-1e53-436c-a6e7-feeac8ffde14
|
2023
|
Which of the following statements is true for the nitrogen metabolism of amino acids?:
|
The first step in nitrogen elimination is usually the transfer of the αamino group to α-ketoglutarate.
|
Nitrogen is released in the digestion process by pancreatic proteases.
|
Transamination reactions are highly irreversible.
|
Chemistry
|
Aminotransferases are nonspecific and act on all amino acids.
| 162 | 2 |
c51102e7-04d2-498d-877e-e03bd021a8b0
|
2023
|
Which of the following statements is false for the synthesis of deoxyribonucleotides?:
|
The source of reducing equivalents is NADPH + H+.
|
The key enzyme is ribonucleotide reductase.
|
They are directly synthesized from deoxyribose.
|
Chemistry
|
The dATP allosterically inhibits synthesis.
| 163 | 4 |
3e57ddfd-4186-4dc2-a9ff-ccc92a93e6b6
|
2023
|
The pKa values of aspartic acid are 2.1; 3.9 and 9.8. Its isoelectric point (pI) is:
|
5.3
|
7.0
|
3.9
|
Chemistry
|
3.0
| 165 | 3 |
a8c22b6b-3fcc-4147-91d2-c852fc451f07
|
2023
|
Proteins intended to be secreted are synthesized in:
|
The rough endoplasmic reticulum.
|
The free polysomes.
|
The smooth endoplasmic reticulum.
|
Chemistry
|
The Golgi apparatus.
| 166 | 2 |
1573b32d-4cca-40a1-b13c-00c0afd3a98d
|
2023
|
Squalene is a precursor of:
|
Prostaglandins.
|
Sphingosine.
|
Cholesterol.
|
Chemistry
|
Arachidonic acid.
| 167 | 4 |
98fc6060-3328-4864-8a6e-5b1bd4cfb767
|
2023
|
Each fatty acid oxidation cycle:
|
It uses up two molecules of NADH.
|
Releases a molecule of acetyl-CoA.
|
It causes dehydration.
|
Chemistry
|
It generates two molecules of FADH2.
| 168 | 1 |
c8796c36-dc77-44cf-a206-cc095739c1ef
|
2023
|
The malate-aspartate shuttle:
|
It serves to transfer the electrons from NADH in the cytosol to the mitochondria.
|
It allows the regeneration of cytosolic NADH necessary for glycolysis.
|
It is an electron transport complex.
|
Chemistry
|
Transfer the electrons from NADH to citrate.
| 169 | 2 |
0dac7e02-05d9-430c-931c-354e9359f44d
|
2023
|
Regarding the Michaelis-Menten constant (Km):
|
A high value of Km can be related to great stability of the enzyme-substrate complex.
|
It is expressed in units of speed.
|
It remains constant for enzymes of the same class.
|
Chemistry
|
It equates to the substrate concentration required to reach half of the maximum speed.
| 170 | 3 |
5a8e9dff-4e80-45cb-bdf1-10fc7be8e5a3
|
2023
|
What wavelength would be strongly absorbed by a red colored solution?
|
585 nm.
|
450 nm.
|
650 nm.
|
Chemistry
|
600 nm.
| 171 | 1 |
1c5b1ddc-56e9-4f40-8600-b83c1094c91f
|
2023
|
Which of the following biochemical processes is promoted by insulin?:
|
Gluconeogenesis.
|
Glycogenolysis.
|
Uptake of glucose by cells.
|
Chemistry
|
Lipolysis.
| 172 | 4 |
c1d515c1-634e-4dfb-b95e-df7e99206bcd
|
2023
|
The electrophoretic movement of proteins towards the anode decreases when it is increased:
|
The ionic strength of the buffer.
|
The pH of the buffer.
|
The voltage.
|
Chemistry
|
The intensity of the current.
| 173 | 2 |
05a85886-11bd-4d17-ba82-8e646bc28463
|
2023
|
Restriction endonucleases:
|
They are used for the formation of hybrid molecules through recombination.
|
They hydrolyze phosphoester bonds starting from the 5' ends of the DNA.
|
They recognize and cut the DNA in sequences free of nucleosomes.
|
Chemistry
|
They recognize and cut the DNA in specific sequences.
| 174 | 3 |
8137317c-f735-4576-a666-1c28fdb39e48
|
2023
|
Enzymes alter:
|
Reaction rates but not equilibria.
|
Reaction rates and equilibrums.
|
The affinity for substrates.
|
Chemistry
|
Only the balances of the reaction.
| 175 | 2 |
79a539a6-0f08-4ef7-89a6-957588698a11
|
2023
|
The polymerase chain reaction allows:
|
Amplify specific DNA sequences.
|
Mapping and identifying the genes of a genome.
|
Locate structures in RNA sequences.
|
Chemistry
|
Understand the topology of specific DNA sequences.
| 176 | 2 |
167a8346-8a79-45bc-9652-63fdc57d7eb8
|
2023
|
Topoisomerases are enzymes:
|
That allow the hybridization between two topological isomers of DNA.
|
That denature the double helix structure of DNA.
|
That they have helicase-primase activity.
|
Chemistry
|
That increase or decrease the degree of DNA unwinding.
| 177 | 3 |
88194ab5-0c0c-44f3-8170-e65b558482c2
|
2023
|
The proofreading activity of prokaryotic DNA polymerase I is an activity:
|
5'-3' Transesterification.
|
5´-3´ Polymerizing.
|
3'-5' Exonuclease.
|
Chemistry
|
5' to 3' Exonuclease.
| 178 | 4 |
771673f0-f79b-4342-b4d5-581c832eacd0
|
2023
|
About Vitamin B12:
|
Participates in carboxylation reactions.
|
It is also known as pyridoxine or pyridoxal.
|
It contains manganese in its structure.
|
Chemistry
|
Its activity is linked to that of folic acid.
| 179 | 3 |
5d02ae32-3c57-473d-94b3-a3a067576104
|
2023
|
Which of the following amino acids is abbreviated with an E in the one-letter nomenclature?
|
Glutamic acid.
|
Aspartic acid.
|
Glutamine.
|
Chemistry
|
Asparagine.
| 180 | 2 |
c520b90a-e45b-472a-b9e4-db0247479e7c
|
2023
|
In molecular biology, what is the temperature called at which half of the copies of a DNA sequence are in the form of a single strand and the other half are in the form of a double strand?
|
Conjugation temperature.
|
Hybridization temperature.
|
Melting temperature.
|
Chemistry
|
Transformation temperature.
| 181 | 4 |
490abb4d-7235-46f4-8208-d411c1e4e2da
|
2023
|
This is true in relation to euchromatin:
|
It is transcriptionally active.
|
It is very condensed.
|
Contains highly repetitive DNA sequences.
|
Chemistry
|
It constitutes 90% of the total chromatin.
| 182 | 2 |
0fdba93f-478f-4795-b63b-12ea4de4c0ac
|
2023
|
Indicate the incorrect statement regarding the Krebs Cycle:
|
It plays a crucial role as a link between the different metabolic pathways.
|
It generates two GTP molecules.
|
It is an amphibolic pathway.
|
Chemistry
|
It provides precursors for many biosynthetic pathways through its intermediates.
| 184 | 1 |
476719ec-3545-4f97-a79b-6da81446538b
|
2023
|
Which of the following amino acids contains sulfur?:
|
Methionine.
|
Leucine.
|
Proline.
|
Chemistry
|
Tryptophan.
| 185 | 2 |
ffd23fef-5afe-4a15-9a6c-1df81f976904
|
2023
|
Which of the following statements about the beta-sheet structure of proteins is not true?:
|
It is stabilized through hydrogen bond bridges.
|
The chains can only be arranged in a parallel manner, that is, in the same direction.
|
It is a type of secondary structure that is widely spread.
|
Chemistry
|
The side chains are arranged either above or below the plane.
| 186 | 1 |
912a6135-0781-4a1b-ae2c-599d694f0006
|
2023
|
In the kinetics of an enzyme, competitive reversible inhibitors:
|
Both the Km and the Vmax decrease.
|
They reduce the Km without altering the Vmax.
|
They increase the Km without modifying the Vmax.
|
Chemistry
|
They increase the Km and decrease the Vmax.
| 187 | 4 |
b23e683b-679f-41e5-9234-0f2838735499
|
2023
|
The Krebs cycle or citric acid cycle is favored by high cellular concentrations of:
|
ADP and NAD+.
|
ATP and NADH.
|
ATP and NAD+.
|
Chemistry
|
ADP and NADH.
| 189 | 2 |
a0227cf1-d1dd-4593-841e-88ca6092a5d1
|
2023
|
In reference to vitamins, indicate the correct answer:
|
Excessive supplementation of biotin can cause ataxia and sensory neuropathy.
|
The function of thiamine is to transfer units of a carbon atom in the synthesis processes of RNA and amino acids.
|
A deficiency of pyridoxine can cause pellagra.
|
Chemistry
|
Vitamin C is involved in the formation of hydroxyproline in collagen.
| 190 | 3 |
cc961e72-38fe-4195-9564-c1f3b0fb2dbf
|
2023
|
Regarding erythropoietin, indicate the correct answer:
|
It inhibits the production of red blood cells in the bone marrow.
|
It is a lipoprotein synthesized at the renal level.
|
Increases in progressive renal failure.
|
Chemistry
|
The tubular renal cells release it when the oxygen pressure decreases.
| 191 | 3 |
7ed6d347-5442-4da6-82fb-d5cddad8b1fb
|
2023
|
At the isoelectric point of amino acids and proteins:
|
The net charge of each ionizable group is zero.
|
Both ionizable groups of the amino acid have the same charge.
|
The charge is the same for all amino acids at a certain pH.
|
Chemistry
|
The algebraic sum of the charges of the ionizable groups is zero.
| 192 | 3 |
2e524b34-6d62-4d5a-b43a-bb78b1e968d0
|
2023
|
If in a double-stranded DNA there is a 20% mole of guanine, what is the mole percentage of thymine?:
|
30%.
|
20%.
|
It cannot be known with that only piece of information.
|
Chemistry
|
80%.
| 193 | 2 |
3f8dbe84-824e-43c0-bb68-e7ef24f998db
|
2023
|
The high fidelity of the protein synthesis process is primarily due to:
|
The presence of initiation and elongation factors specific for each aminoacyl-tRNA.
|
The activity of the peptidyl transferase enzyme.
|
The corrective activity of the aminoacyl-tRNA synthetase.
|
Chemistry
|
The coupling between the ribosome and the transfer RNA.
| 194 | 4 |
a35f5d40-80f1-4918-b7a3-75be46e10354
|
2023
|
Genetic imprinting (imprinting) is the:
|
Absence of certain genes in the genome.
|
Differential expression of one of the alleles.
|
Presence in the genome of genes that allow individual identification.
|
Chemistry
|
Expression of genes causing diseases.
| 195 | 1 |
5cc86048-c0a0-4fd9-8ac2-269113792383
|
2023
|
Steroid hormones act at the cellular level:
|
Through the formation of a second messenger.
|
Inhibiting pre-existing enzymes.
|
Modifying the concentration of intracellular ionic calcium.
|
Chemistry
|
Through the regulation of gene expression.
| 196 | 3 |
6c2e5ee5-28be-40a3-8a88-c8f34a9bf114
|
2023
|
In reference to the Klenow fragment, indicate the false statement:
|
Its great advantage is its stability at high temperatures.
|
It is a fragment of the enzyme DNA polymerase I.
|
It has polymerase activity and 3´→5´ exonuclease activity.
|
Chemistry
|
It is used for the filling of 3´ ends of DNA fragments.
| 197 | 2 |
e748a763-1527-4cc4-b636-a2de83baf0b2
|
2023
|
What is the Shine-Dalgarno sequence?
|
A sequence located 6 or 7 nucleotides from the termination codon of RNA translation.
|
A messenger RNA sequence that only exists in prokaryotes.
|
Sequence located 25 nucleotides from the transcription start site.
|
Chemistry
|
A consensus DNA sequence in the promoter region of eukaryotic genes.
| 198 | 1 |
0c68f2c8-f840-4f7c-94dd-87812cfb7c36
|
2023
|
How does the increase in temperature affect the antigen-antibody reaction?
|
It reduces the speed and increases the binding affinity.
|
Increases speed and decreases binding affinity.
|
Decreases the speed and binding affinity.
|
Chemistry
|
Increases the speed and binding affinity.
| 199 | 1 |
0e5fc49a-5889-47b2-96a0-432ef464802c
|
2023
|
Plasmids are:
|
Double-stranded RNA molecules and circular with antibiotic resistance genes.
|
Linear DNA fragments with antibiotic resistance genes.
|
Circular DNA molecules that replicate independently of the host chromosome.
|
Chemistry
|
Circular DNA molecules that replicate in a chromosome-dependent manner of the host.
| 200 | 4 |
d26a110e-b4e1-46f0-8ee4-9833ebae03ee
|
2023
|
Which of the following statements about Pourbaix diagrams is false?:
|
The more oxidized species are found in the upper part of the diagram, while the more reduced species are found in the bottom part.
|
These are graphical representations of the potential (ordinate) as a function of pH (abscissa) for a given element under standard thermodynamic conditions (usually water at 25°C).
|
Two oblique and parallel lines, which represent the oxidation of water (lower line) and the reduction of water (upper line), delimit a zone of the diagram that contains the stable species in aqueous solution.
|
Chemistry
|
The oblique lines indicate reactions between species dependent on both potential and pH.
| 201 | 4 |
a3562641-2dcf-4e02-856a-1c42a02976be
|
2023
|
Which of the following compounds will undergo a rearrangement when subjected to a solvolysis reaction?:
|
3-iodohexane.
|
3-iodo-5-methylhexane.
|
3-iodo-3-methylhexane.
|
Chemistry
|
3-iodo-2-methylhexane.
| 202 | 3 |
68d72fa7-10aa-4023-8a09-a98b394a0222
|
2023
|
What does the Mohs scale measure?:
|
Conductivity.
|
Acidity.
|
Viscosity.
|
Chemistry
|
Hardness.
| 203 | 3 |
3b8f4c4a-6528-49b8-9b05-4f5559c85a76
|
2023
|
Bilirubin is:
|
A biomarker of kidney function.
|
A liver function biomarker.
|
A biomarker of brain function.
|
Chemistry
|
A biomarker of cardiac function.
| 204 | 1 |
987d6baf-a015-46e7-b3a2-4ef05cd5fc8f
|
2023
|
What type of capillary electrophoresis uses a continuous and stable pH gradient?
|
Capillary Gel Electrophoresis (CGE).
|
Capillary Zone Electrophoresis (CZE).
|
Capillary Isoelectric Focusing (CIEF).
|
Chemistry
|
Capillary Isotachophoresis (CITP).
| 205 | 4 |
bb34c60b-f789-44a4-9cd0-8518293a4a2f
|
2023
|
What does the UFI code, which is mandatory on the label of products classified for their health risks, correspond to?
|
QR Code that includes information about the batch and expiry date of a product.
|
Alphanumeric code that allows the unique identification of a product during an emergency call to a toxicology center.
|
QR code that allows for the unique identification of a product during an emergency call to a poison control center.
|
Chemistry
|
Barcode that includes information about the batch and expiration date of a product and allows it to be identified during an emergency.
| 206 | 1 |
0e8cf449-a695-4b23-ad01-7fc6d3a3784b
|
2023
|
Molecular fluorescence:
|
It becomes more intense as the viscosity of the solvent decreases.
|
It becomes more intense as the temperature increases.
|
It exhibits a higher quantum yield of emission in mediums with elevated levels of oxygen.
|
Chemistry
|
It is particularly favored in rigid molecules.
| 207 | 3 |
b348ca76-7175-4fdc-a50e-cae4fa389392
|
2023
|
Consider the following reaction: C(s) + H2O(g) ⇌ CO(g) + H2(g). At equilibrium at a given temperature, the concentrations are: [H2O]=0.12 M and [CO]=[H2]=1.2 M. If all these concentrations increase by 0.5 M simultaneously, which of the following responses is true?:
|
More products will be formed.
|
More H2O(g) will be formed.
|
The value of Kc does not change, therefore, nothing happens.
|
Chemistry
|
It is necessary to know the value of Kp to understand what is happening.
| 208 | 2 |
fb7ba7f8-24f2-4650-8ff6-bf7b03a37a10
|
2023
|
Every measurement carries an associated error. Systematic errors are those produced by measuring equipment or by analysts who:
|
They always occur in the same direction, causing a bias.
|
Corrections are made by performing a large number of measurements.
|
They are due to chance and cannot be eliminated, although they can be minimized.
|
Chemistry
|
They cannot be corrected.
| 209 | 2 |
438ad76d-dfa8-43ba-be3e-f4d6f23237ee
|
2023
|
What is the enzyme responsible for unwinding the double helix during the DNA replication process?
|
DNA gyrase.
|
Primase.
|
DNA polymerase.
|
Chemistry
|
DNA helicase.
| 210 | 3 |
381842ed-2235-4372-a3f9-54cf800595b5
|
2023
|
What is the process called in which hydrogen sulfide present in natural gas is removed, producing sulfur?
|
Claus Process.
|
Frasch Process.
|
Lead chamber process.
|
Chemistry
|
Kroll Process.
| 1 | 2 |
54612900-f392-446f-bb88-3dd93805ab1f
|
2022
|
The most stable allotrope form of elemental phosphorus is:
|
Red phosphorus.
|
White phosphorus.
|
Black phosphorus.
|
Chemistry
|
The violet phosphorus.
| 2 | 4 |
0261a4a0-4856-4928-865d-e1508965662d
|
2022
|
Is it possible to obtain any compound in oxidation state 8?
|
No, but it can reach oxidation state 7, for example OsF7.
|
Yes, for example, the OsO4 and the RuO4.
|
No, but it can reach oxidation state 7, for example OsBr7.
|
Chemistry
|
No, but oxidation state 7 can be achieved, for example OsCl7.
| 3 | 1 |
fab5715a-6618-4b27-9299-edd1a4d06892
|
2022
|
Which of the following statements about ionic compounds is false?:
|
They have high melting points.
|
All ionic compounds are solids and their crystals are hard and brittle.
|
Almost all dissolve in very polar solvents (like water) generating solutions that conduct electricity.
|
Chemistry
|
If they do not decompose when heated, in a melted state they act as insulators.
| 4 | 3 |
81fbb51f-f137-4f8e-9ea3-20d7b996265e
|
2022
|
With which elements does fluorine form compounds?
|
With all except the noble gases.
|
With all except He, Ne and Ar.
|
With all except the other halogens.
|
Chemistry
|
With all except the alkalines.
| 5 | 1 |
b6c9da20-6362-4164-954e-657730e835f5
|
2022
|
What is optical fiber?:
|
Ultra high purity thin silica fiber.
|
Ultra high purity thin iron oxide fiber.
|
Thin silica fiber with aluminum oxide impurities.
|
Chemistry
|
Thin fiber of iron oxide with impurities of manganese oxide.
| 6 | 2 |
6ca8eb2d-7080-4076-94d6-ee68775588c8
|
2022
|
The thiosulfate anion was widely used in photography, it is very commonly used as a reducer and has various uses in Medicine. What is its formula?
|
S2O32-
|
S4O62-.
|
S2O72-.
|
Chemistry
|
HSO3-.
| 7 | 2 |
02758be5-efb4-4719-be41-374af41c1830
|
2022
|
Cobalt:
|
In its metallic form, it has no magnetic properties.
|
It is a soft metal with a metallic color.
|
It is an essential element for living beings.
|
Chemistry
|
It is very reactive as a chemical element.
| 8 | 4 |
7eba0f1e-9c36-472f-94e1-47aa658fbc4a
|
2022
|
What type of defect is a Schottky defect?
|
Intrinsic point defect.
|
Extrinsic point defect.
|
Linear defect.
|
Chemistry
|
Extended defect.
| 9 | 2 |
baeb8402-2825-4b40-8359-7991a582d5e5
|
2022
|
Which of the following reactions requires a catalyst to be fast?
|
H2O2 (liquid) + SO2 (gas) → H2SO4.
|
H2O2 (liq.) → H2O (liq.) + ½ O2 (gas).
|
Cl2 + 2 NaOH → NaCl + NaClO + H2O.
|
Chemistry
|
NO (gas) + ½ O2 (gas) → NO2 (gas).
| 10 | 1 |
3c6083dc-35e6-405a-8684-9c91337960b1
|
2022
|
For which of the following elements is the tetrafluoride unknown?:
|
Pr.
|
Ce.
|
Tb.
|
Chemistry
|
Eu.
| 11 | 3 |
001a66cc-d92a-4fd6-9759-ac8917b1d48f
|
2022
|
Mercury exists in nature mainly as cinnabar, HgS. Its formation can be interpreted as an acid-base reaction. What type of reaction is it?
|
The anion is a soft base that reacts with the soft acid cation.
|
The anion is a hard base that reacts with the hard acid cation.
|
The anion is a soft acid that reacts with the soft base cation.
|
Chemistry
|
The anion is a soft base that reacts with the hard acid cation.
| 12 | 2 |
5c8ae19d-6b61-4a34-b1c0-13c6a7e17883
|
2022
|
What is the most abundant metallic element by mass in the human body?
|
Sodium.
|
Magnesium.
|
Calcium.
|
Chemistry
|
Potassium.
| 13 | 4 |
26c6d59f-9fa6-49f6-b742-185c51efc43e
|
2022
|
For the following pairs of chemical species, in which case are both species diamagnetic?
|
29Cu+ and 28Ni.
|
29Cu+ and 30Zn2+.
|
29Cu2+ and 28Ni2+.
|
Chemistry
|
30Zn2+ and 28Ni.
| 14 | 1 |
09eb4bdf-c3bb-4ef6-bbaf-a1f783013570
|
2022
|
What is the idealized formula of apatite?
|
Ca10(PO4)6X2, (X: OH, Cl or F).
|
Ca10(PO4)6X4, (X: OH, Cl, or F).
|
Mg10(PO4)6X3, (X: OH, Cl or F).
|
Chemistry
|
Ca10(PO4)5X2, (X: OH, Cl or F).
| 15 | 2 |
e168e25a-311b-48d9-8948-6fa930d13bf3
|
2022
|
Which metal does the dinitrogen molecule, N2, react with at room temperature?
|
With iron.
|
With lithium.
|
With lead.
|
Chemistry
|
With tungsten.
| 16 | 1 |
745abc4b-22a6-44d3-bb3d-6a461f4d2c0f
|
2022
|
If ammonium nitrate (or ammonium nitrate) is considered, it can be affirmed that:
|
Both the nitrate anion and the ammonium cation have tetrahedral structures.
|
It has no industrial/agri-food utility.
|
It decomposes into N2, O2 and H2O when heated at low temperature, but into N2O if done at high temperature.
|
Chemistry
|
It is a hygroscopic compound (it absorbs moisture to form a sticky mass that hardens when the humidity drops) and at the same time a powerful explosive.
| 18 | 3 |
d85ee5ee-f753-4c86-a205-c5e56fcc3cce
|
2022
|
The temperature above which a ferromagnetic material stops behaving as such and begins to behave as a purely paramagnetic material is called:
|
Planck Temperature.
|
Curie Temperature.
|
Rankine Temperature.
|
Chemistry
|
Néel Temperature.
| 19 | 1 |
dd9c13cb-34f6-4cf7-8d4d-927a30c0bb88
|
2022
|
What is the result of the reaction of H2S with SO2 at 300º C in the presence of iron oxides?
|
H2S + 2 SO2 → H2S3O4.
|
H2S + SO2 → S2O + H2O.
|
2 H2S + SO2 → 3/8 S8 + 2 H2O.
|
Chemistry
|
H2S + 3 SO2 → H2S4O6.
| 20 | 4 |
71f08fce-281b-4f16-964a-419dd0adedd7
|
2022
|
What type of carbide is WC?
|
Covalent carbide.
|
Ionic carbide.
|
Saline carbide.
|
Chemistry
|
Interstitial carbide.
| 21 | 3 |
222253e0-44b4-44e7-9cd3-179a4e53409e
|
2022
|
Hydrogen chloride:
|
It is extremely soluble in water, being able to generate concentrated solutions that contain approximately 38% of the acid by mass, a 12M concentration.
|
In its pure state and at room temperature, it is a corrosive liquid with a strongly irritating smell.
|
It does not oxidize the metallic Zn since the chloride anion (in oxidation state -1) can no longer be reduced any further.
|
Chemistry
|
In an aqueous solution, it is a strong acid, although not as strong as hydrofluoric acid.
| 22 | 2 |
c13fd16f-0c8b-4c3e-8481-007744b1526d
|
2022
|
What is the structure of quartz made of?
|
Tetrahedrons [SiO4] sharing edges.
|
Tetrahedrons [SiO4] sharing vertices.
|
Octahedrons [SiO6] sharing edges.
|
Chemistry
|
Octahedrons [SiO6] sharing vertices.
| 23 | 1 |
fc4d09be-d74a-49e1-90d9-37bb95dee31f
|
2022
|
Indicate the main product of the combustion of metallic potassium with excess oxygen:
|
Potassium peroxide.
|
Potassium oxide.
|
Potassium ozonide.
|
Chemistry
|
Potassium superoxide.
| 24 | 3 |
45635944-2397-48d8-afed-1e2fb715a19c
|
2022
|
Which of the following compounds undergoes hydrolysis in water?:
|
MoF3.
|
TiCl4.
|
MnF2.
|
Chemistry
|
MoCl3.
| 25 | 1 |
9b04cadb-454e-43b1-8de7-0d1e52eb01b7
|
2022
|
Indicate which of the following statements is false, according to Fajans' rules:
|
A cation is more polarizing if it is small and has a high positive charge.
|
The deformation of the spherical shape of an ideal anion is known as polarization.
|
The anions that do not have a noble gas configuration are not polarizable.
|
Chemistry
|
An anion is more easily polarized if it is large and has a large negative charge.
| 26 | 4 |
58b1bab6-1ab8-4039-948d-37ffb53db46a
|
2022
|
What is the name of the phenomenon in which a force acts on a moving electron or hole due to the action of a magnetic field perpendicular to the direction of movement?
|
Thompson Effect.
|
Joule Effect.
|
Einstein Effect.
|
Chemistry
|
Hall Effect.
| 27 | 3 |
fbdaa37a-f217-4216-9858-d0ce3d61119d
|
2022
|
What are the methyl transfer reactions of cobalamins based on?
|
In the high electrophilicity of square planar Co (I).
|
In the high nucleophilicity of square planar Co (I).
|
In the low electrophilicity of tetrahedral Co (II).
|
Chemistry
|
On the low nucleophilicity of tetrahedral Co (II).
| 28 | 1 |
9df47702-92a3-4525-90de-c2f2ebf880a0
|
2022
|
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