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Physical Chemistry Test

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The ------------------------ ionisation converts ions from liquid to gaseous phase for analysis.

  1. thermospray

  2. sonic spray

  3. probe electrospray

  4. electrospray


Correct Option: A
Explanation:

Thermospray is a form of atmospheric pressure ionization in mass spectrometry. It transfers ions from the liquid phase to the gaseous phase for analysis. It is particularly useful in liquid chromatography-mass spectrometry.

The ionized atoms are usually referred as

  1. polaritons

  2. fermion

  3. heavy ion

  4. polaron


Correct Option: C
Explanation:

Heavy ion refers to an ionized atom which is usually heavier than helium. Heavy-ion physics is devoted to the study of extremely hot nuclear matter and the collective effects appearing in such systems, differing from particle physics, which studies the interactions between elementary particles.

The measure of bond strength is

  1. bond energy

  2. bond dipole moment

  3. bond length

  4. bond order


Correct Option: A
Explanation:

In chemistry, bond energy (E) is a measure of bond strength in a chemical bond. It is the heat required to break one Mole (unit) of molecules into their individual atomsb

The interaction between a metal hydride bond with another proton donor is known as

  1. dihydrogen bond

  2. dihydrogen complexes

  3. symmetric hydrogen bond

  4. mechanical bond


Correct Option: A
Explanation:

In chemistry, a dihydrogen bond is a kind of hydrogen bond, an interaction between a metal hydride bond and an OH or NH group or another proton donor.

A carbohydrate molecule is joined to another group through ------------------ bonds.

  1. a glycosidic bond

  2. sigma bonds

  3. a hydrogen bond

  4. pi bonds


Correct Option: A
Explanation:

A glycosidic bond is formed between the hemiacetal group of a saccharide (or a molecule derived from a saccharide) and the hydroxyl group of some organic compound such as an alcohol.It is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.

Which of the following terms describes the coordination of contiguous atoms of a ligand to a central atom?

  1. Aromaticity

  2. Polarity

  3. Hapticity

  4. Stacking


Correct Option: C
Explanation:

The term hapticity is used to describe how a group of contiguous atoms of a ligand are coordinated to a central atom.

The process of overlap of one p-orbital with another p orbital across an intervening sigma bond is known as

  1. conjugation

  2. resonance

  3. hyperconjugation

  4. cross-conjugation


Correct Option: A
Explanation:

Conjugation is the overlap of one p-orbital with another across an intervening sigma bond (in larger atoms d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent single bonds. They allow a delocalization of pi electrons across all the adjacent aligned p-orbitals.

Among the following forces, --------------------- is a combination of hydrogen bonding and electrostatic interactions.

  1. agostic bond

  2. dipolar bond

  3. π backbonding

  4. salt bond


Correct Option: D
Explanation:

Salt bond falls into the broader category of noncovalent interactions. A salt bond is actually a combination of two noncovalent interactions: hydrogen bonding and electrostatic interactions .This is most commonly observed to contribute stability to the entropically unfavourable folded conformation of proteins.

The bonding in hypervalent molecules is explained by ------------------- bonds.

  1. a three-centre two-electron bond

  2. the three-centre-four-electron bond

  3. a four-centre two-electron bond

  4. none of these


Correct Option: B
Explanation:

The 3-centre-4-electron bond is a model used to explain bonding in hypervalent molecules such as phosphorus pentafluoride, sulfur hexafluoride, the xenon fluorides, and the bifluoride ion.

The net electric charge of an ion is termed as

  1. the electron affinity

  2. electronegativity

  3. electrovalency

  4. electron deficiency


Correct Option: C
Explanation:

Electrovalency is a measurement of the net electric charge of an ion and is used when balancing chemical reactions. Electrovalency is related to the concepts of electronegativity and valence electrons, and indicates the number of electrons necessary for an ion to have a balanced electric charge.

The dissociation lifetime of ------------------- bond increases with tensile force applied to the bond.

  1. a carbon-carbon bond

  2. carbon-hydrogen bond

  3. catch bond

  4. cation-π interaction


Correct Option: C
Explanation:

A catch bond is a type of noncovalent bond whose dissociation lifetime increases with tensile force applied to the bond. Normally, bond lifetimes are expected to diminish with force.

Which of the following terms refers to the number of atoms in a ligand bound to a central atom in a coordination complex?

  1. Denticity

  2. Indirect agonist

  3. Cooperativity

  4. Homoaromaticity


Correct Option: A
Explanation:

Denticity refers to the number of atoms in a single ligand that bind to a central atom in a coordination complex.

Allostery is a general mechanism of regulation in biology. Which of the following is regarded as a special case of allostery?

  1. Chemical specificity

  2. Communal aggregation

  3. Cooperative binding

  4. Pseudorotation


Correct Option: C
Explanation:

Cooperative binding is a special case of allostery. Cooperative binding requires that the macromolecule have more than one binding site, since cooperativity results from the interactions between binding sites.

The covalent bond involving 12 bonding electrons is a

  1. delta bond

  2. quadruple bond

  3. quintuple bond

  4. Sextuple bond


Correct Option: D
Explanation:

A sextuple bond is a type of covalent bond involving 12 bonding electrons and in which the bond order is 6. The only known molecules with true sextuple bonds are the diatomic dimolybdenum (Mo2) and ditungsten (W2), which exist in the gaseous phase.

Which of the following techniques determines the elemental composition through electromagnetic or mass spectrum ?

  1. Mass spectrometry

  2. Atomic emission spectroscopy

  3. Atomic absorption spectroscopy

  4. Atomic spectroscopy


Correct Option: D
Explanation:

Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum. Atomic spectroscopy is closely related to other forms of spectroscopy.

Silicon, quartz and graphite are the examples of ------------------- solids.

  1. metallic

  2. ionic

  3. molecular

  4. covalent


Correct Option: D
Explanation:

A network covalent solid consists of atoms held together by a network of covalent bonds and hence can be regarded as a single, large molecule. The classic example is diamond; other examples include silicon, quartz, and graphite.

Gibbs free energy is negative in a/an

  1. endergonic reaction

  2. metamorphic reaction

  3. exergonic reaction

  4. isodesmic reaction


Correct Option: C
Explanation:

An exergonic reaction is a chemical reaction where the change in the Gibbs free energy is negative, indicating a spontaneous reaction.

The reversible inclusion of a group between two different groups is known as

  1. aurophilicity

  2. intercalation

  3. stacking

  4. metal aromaticity


Correct Option: B
Explanation:

Intercalation is the reversible inclusion of a molecule (or group) between two other molecules (or groups). Examples include DNA intercalation and graphite intercalation compounds.

When one mole of matter is transformed from one form into another under standard conditions, the enthalphy of reaction is termed as

  1. the standard enthalpy change of formation

  2. the standard enthalpy change of combustion

  3. the standard enthalpy of reaction

  4. the standard enthalpy of neutralisation


Correct Option: C
Explanation:

The standard enthalpy of reaction is the enthalpy change that occurs in a system when one mole of matter is transformed by a chemical reaction under standard conditions.

Bond involving the dispersed variations of electromagnetic interactions is

  1. a non-covalent bond

  2. bent bonds

  3. low-barrier hydrogen bond

  4. polar bond


Correct Option: A
Explanation:

A non-covalent bond is a type of chemical bond, typically between macromolecules, that does not involve the sharing of pairs of electrons, but rather involves more dispersed variations of electromagnetic interactions.

Gas phase ions, from a solid sample, are produced in which method?

  1. Electron ionization

  2. Chemical ionization

  3. Ion-attachment ionization

  4. Spark ionization


Correct Option: D
Explanation:

Spark ionization is a method used to produce gas phase ions from a solid sample. The prepared solid sample is vapourized and partially ionized by an intermittent discharge or spark.

Which of the following is used to create charged particles?

  1. Ion bombardment

  2. An ion beam

  3. An ion source

  4. An ion thruster


Correct Option: C
Explanation:

An ion source is an electro-magnetic device that is used to create charged particles. These are used primarily to form ions for mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters and ion engines.

The forces arising from the quantum induced instantaneous polarization multipoles in molecules is/are

  1. van der Waals force

  2. london dispersion forces

  3. intramolecular force

  4. intermolecular forces


Correct Option: B
Explanation:

London dispersion force is a weak intermolecular force arising from the quantum induced instantaneous polarization multipoles in molecules. They can act between molecules without permanent multipole moments.These are exhibited by nonpolar molecules because of the correlated movements of the electrons in interacting molecules.

Which of the following particle accelerators uses a donut-shaped ring magnet ?

  1. Cyclotrons

  2. FFAG accelerators

  3. Betatron

  4. Synchrotron


Correct Option: C
Explanation:

These machines, use a donut-shaped ring magnet with a cyclically increasing B field, but accelerate the particles by induction from the increasing magnetic field, as if they were the secondary winding in a transformer, due to the changing magnetic flux through the orbit.

Which of the following effects is due to the substituents or functional groups in a chemical compound?

  1. Electromeric effect

  2. The mesomeric effect

  3. The inductive effect

  4. Inert pair effect


Correct Option: B
Explanation:

The mesomeric effect or resonance effect in chemistry is a property of substituents or functional groups in a chemical compound. The effect is used in a qualitative way and describes the electron withdrawing or releasing properties of substituents based on relevant resonance structures and is symbolized by the letter M.

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