Q. In the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g), what will happen if Cl2 is removed from the system?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Increase the rate of reaction
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Solution
Removing Cl2 decreases its concentration, causing the equilibrium to shift to the right to produce more Cl2.
Correct Answer:
B
— Shift to the right
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Q. In the van der Waals equation, what do the 'a' and 'b' constants represent?
A.
Attraction and volume correction
B.
Pressure and temperature
C.
Density and molar mass
D.
Entropy and enthalpy
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Solution
'a' accounts for the attractive forces between particles, while 'b' accounts for the volume occupied by the gas particles in the van der Waals equation.
Correct Answer:
A
— Attraction and volume correction
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Q. In titration, what is the purpose of the indicator?
A.
To increase the reaction rate
B.
To provide a visual signal of endpoint
C.
To stabilize the pH
D.
To dilute the solution
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Solution
The indicator in titration provides a visual signal of the endpoint, indicating when the reaction is complete.
Correct Answer:
B
— To provide a visual signal of endpoint
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Q. In UV-Vis spectroscopy, what does a higher absorbance indicate about the concentration of a solution?
A.
Lower concentration
B.
Higher concentration
C.
No correlation
D.
Increased temperature
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Solution
According to the Beer-Lambert Law, higher absorbance indicates a higher concentration of the absorbing species in the solution.
Correct Answer:
B
— Higher concentration
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Q. In UV-Vis spectroscopy, what does a higher absorbance indicate about the concentration of a sample?
A.
Lower concentration
B.
Higher concentration
C.
No correlation
D.
Increased path length
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Solution
According to Beer-Lambert Law, higher absorbance indicates a higher concentration of the absorbing species.
Correct Answer:
B
— Higher concentration
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Q. In UV-Vis spectroscopy, what does a higher absorbance indicate?
A.
Lower concentration of the analyte
B.
Higher concentration of the analyte
C.
Higher wavelength of light
D.
Lower energy of light
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Solution
A higher absorbance indicates a higher concentration of the analyte, as per the Beer-Lambert Law.
Correct Answer:
B
— Higher concentration of the analyte
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Q. In UV-Vis spectroscopy, what does a higher absorbance value indicate?
A.
Lower concentration of the analyte
B.
Higher concentration of the analyte
C.
Higher wavelength of light
D.
Lower path length of the sample
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Solution
A higher absorbance value indicates a higher concentration of the analyte, according to Beer-Lambert law.
Correct Answer:
B
— Higher concentration of the analyte
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Q. In UV-Vis spectroscopy, what does a higher molar absorptivity indicate?
A.
Lower concentration
B.
Higher concentration
C.
More efficient light absorption
D.
Less efficient light absorption
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Solution
A higher molar absorptivity indicates that a substance is more efficient at absorbing light at a given wavelength.
Correct Answer:
C
— More efficient light absorption
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Q. In UV-Vis spectroscopy, what does a peak at 260 nm typically indicate?
A.
Presence of proteins
B.
Presence of nucleic acids
C.
Presence of carbohydrates
D.
Presence of lipids
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Solution
A peak at 260 nm in UV-Vis spectroscopy typically indicates the presence of nucleic acids, as they absorb light at this wavelength.
Correct Answer:
B
— Presence of nucleic acids
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Q. In UV-Vis spectroscopy, what does a peak at 280 nm typically indicate?
A.
Presence of nucleic acids
B.
Presence of proteins
C.
Presence of carbohydrates
D.
Presence of lipids
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Solution
A peak at 280 nm typically indicates the presence of proteins, particularly due to the absorbance of aromatic amino acids.
Correct Answer:
B
— Presence of proteins
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Q. In UV-Vis spectroscopy, what does a peak in the absorbance spectrum indicate?
A.
The presence of a specific ion
B.
The concentration of a gas
C.
The molecular weight of a compound
D.
The boiling point of a solution
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Solution
A peak in the absorbance spectrum indicates the presence of a specific ion or compound that absorbs light at that wavelength.
Correct Answer:
A
— The presence of a specific ion
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Q. In UV-Vis spectroscopy, what does a peak in the absorption spectrum indicate?
A.
The presence of impurities
B.
The concentration of the sample
C.
A specific electronic transition
D.
The temperature of the sample
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Solution
A peak in the absorption spectrum corresponds to a specific electronic transition of electrons within the molecule.
Correct Answer:
C
— A specific electronic transition
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Q. In UV-Vis spectroscopy, what does a shift in the absorption peak indicate?
A.
Change in concentration
B.
Change in pH
C.
Change in molecular structure
D.
Change in temperature
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Solution
A shift in the absorption peak in UV-Vis spectroscopy often indicates a change in molecular structure, such as the formation of new bonds or changes in electronic transitions.
Correct Answer:
C
— Change in molecular structure
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Q. In UV-Vis spectroscopy, what does the Beer-Lambert law relate?
A.
Wavelength and energy
B.
Absorbance and concentration
C.
Frequency and intensity
D.
Temperature and pressure
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Solution
The Beer-Lambert law relates absorbance to concentration, indicating that absorbance increases linearly with concentration of the absorbing species.
Correct Answer:
B
— Absorbance and concentration
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Q. In UV-Vis spectroscopy, what is the effect of increasing the path length of the sample cell?
A.
Decreases absorbance
B.
Increases absorbance
C.
No effect on absorbance
D.
Increases transmittance
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Solution
Increasing the path length of the sample cell increases the absorbance according to the Beer-Lambert Law, as absorbance is directly proportional to path length.
Correct Answer:
B
— Increases absorbance
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Q. In Werner's theory, what does the term 'primary valence' refer to?
A.
The oxidation state of the metal
B.
The number of ligands
C.
The type of ligands
D.
The geometry of the complex
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Solution
Primary valence refers to the oxidation state of the central metal atom in a coordination compound.
Correct Answer:
A
— The oxidation state of the metal
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Q. In Werner's theory, what is the role of ligands in coordination compounds?
A.
To provide electrons to the metal ion
B.
To stabilize the oxidation state of the metal
C.
To determine the color of the complex
D.
To increase the coordination number
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Solution
Ligands act as electron donors to the metal ion, forming coordinate covalent bonds and stabilizing the coordination complex.
Correct Answer:
A
— To provide electrons to the metal ion
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Q. In which application is hydrogen used as a reducing agent?
A.
Electrolysis
B.
Metal extraction
C.
Acid-base neutralization
D.
Combustion
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Solution
Hydrogen acts as a reducing agent in the extraction of metals from their ores, such as in the reduction of metal oxides.
Correct Answer:
B
— Metal extraction
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Q. In which molecule is the bond angle closest to 120°?
A.
H2O
B.
CO2
C.
BF3
D.
NH3
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Solution
BF3 has a trigonal planar geometry with bond angles of approximately 120°.
Correct Answer:
C
— BF3
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Q. In which of the following compounds does hydrogen act as a Lewis acid?
A.
H2O
B.
HCl
C.
BF3
D.
H2
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Solution
In HCl, hydrogen can act as a Lewis acid by accepting an electron pair.
Correct Answer:
B
— HCl
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Q. In which of the following compounds does hydrogen exhibit an oxidation state of -1?
A.
H2O
B.
HCl
C.
NaH
D.
H2O2
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Solution
In NaH (sodium hydride), hydrogen has an oxidation state of -1.
Correct Answer:
C
— NaH
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Q. In which of the following compounds does the central atom exhibit sp3d2 hybridization?
A.
SF6
B.
XeF4
C.
NH3
D.
CCl4
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Solution
In SF6 (sulfur hexafluoride), the sulfur atom is sp3d2 hybridized, allowing it to form six sigma bonds with fluorine atoms.
Correct Answer:
A
— SF6
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Q. In which of the following compounds is the bond angle approximately 109.5 degrees?
A.
H2O
B.
NH3
C.
CH4
D.
BF3
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Solution
CH4 has a tetrahedral geometry with bond angles of approximately 109.5 degrees.
Correct Answer:
C
— CH4
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Q. In which of the following compounds is the central atom sp3 hybridized?
A.
BeCl2
B.
CH4
C.
CO2
D.
NH3
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Solution
In CH4, the carbon atom has four bonding pairs and no lone pairs, leading to sp3 hybridization.
Correct Answer:
B
— CH4
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Q. In which of the following coordination compounds does hydrogen act as a ligand?
A.
[Fe(H2O)6]2+
B.
[Cu(NH3)4]2+
C.
[CoCl4]2-
D.
[Ag(CN)2]-
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Solution
In the complex [Fe(H2O)6]2+, water (H2O) acts as a ligand, coordinating with the iron ion.
Correct Answer:
A
— [Fe(H2O)6]2+
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Q. In which of the following molecules does hydrogen bonding occur?
A.
CH4
B.
H2O
C.
CO2
D.
N2
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Solution
Hydrogen bonding occurs in H2O due to the presence of highly electronegative oxygen atoms bonded to hydrogen, creating strong dipole interactions.
Correct Answer:
B
— H2O
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Q. In which of the following molecules is the bond length the shortest?
A.
C2H2
B.
C2H4
C.
C2H6
D.
C2
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Solution
C2 has a triple bond between the two carbon atoms, resulting in the shortest bond length compared to the others.
Correct Answer:
D
— C2
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Q. In which of the following molecules is the central atom sp2 hybridized?
A.
C2H4
B.
C2H2
C.
CH4
D.
C3H6
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Solution
C2H4 has a double bond between the carbon atoms, indicating sp2 hybridization.
Correct Answer:
A
— C2H4
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Q. In which of the following molecules is the central atom sp3 hybridized?
A.
BeCl2
B.
SiCl4
C.
PCl5
D.
SF6
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Solution
SiCl4 has four bonding pairs and no lone pairs, leading to sp3 hybridization of the silicon atom.
Correct Answer:
B
— SiCl4
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Q. In which of the following processes is hydrogen used to reduce metal ores?
A.
Electrolysis
B.
Hydrometallurgy
C.
Pyrometallurgy
D.
Hydrogen reduction
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Solution
Hydrogen reduction is a process where hydrogen gas is used to reduce metal ores to their metallic form.
Correct Answer:
D
— Hydrogen reduction
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