Chemistry (School & UG)
Q. What is the first ionization energy of lithium (Li) in kJ/mol?
A.
520 kJ/mol
B.
750 kJ/mol
C.
1000 kJ/mol
D.
1500 kJ/mol
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Solution
The first ionization energy of lithium is approximately 520 kJ/mol.
Correct Answer: A — 520 kJ/mol
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Q. What is the first ionization energy of magnesium (Mg) in kJ/mol?
A.
738 kJ/mol
B.
1000 kJ/mol
C.
580 kJ/mol
D.
1200 kJ/mol
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Solution
The first ionization energy of magnesium is approximately 738 kJ/mol.
Correct Answer: A — 738 kJ/mol
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Q. What is the formula for calculating the boiling point elevation?
A.
ΔT_b = i * K_b * m
B.
ΔT_b = K_b / m
C.
ΔT_b = i * K_f * m
D.
ΔT_b = K_f * m
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Solution
The boiling point elevation is calculated using the formula ΔT_b = i * K_b * m, where i is the van 't Hoff factor, K_b is the ebullioscopic constant, and m is the molality.
Correct Answer: A — ΔT_b = i * K_b * m
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Q. What is the formula for the complex formed when iron(III) ions react with thiocyanate ions?
A.
[Fe(SCN)3]
B.
[Fe(SCN)2]
C.
[Fe(SCN)6]3+
D.
[Fe(SCN)4]2+
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Solution
The complex formed is [Fe(SCN)3], where iron(III) ions coordinate with thiocyanate ions.
Correct Answer: A — [Fe(SCN)3]
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Q. What is the formula for the compound formed between hydrogen and sulfur?
A.
H2S
B.
HS
C.
H2SO4
D.
H2SO3
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Solution
The formula for the compound formed between hydrogen and sulfur is H2S (hydrogen sulfide).
Correct Answer: A — H2S
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Q. What is the function of phosphoric acid in soft drinks?
A.
Sweetener
B.
Preservative
C.
Flavor enhancer
D.
Acidulant
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Solution
Phosphoric acid serves as an acidulant, providing a tangy flavor and balancing sweetness in soft drinks.
Correct Answer: D — Acidulant
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Q. What is the function of sodium citrate in food applications?
A.
Preservative
B.
Emulsifier
C.
Buffering agent
D.
Coloring agent
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Solution
Sodium citrate is used as a buffering agent to maintain pH levels in food products.
Correct Answer: C — Buffering agent
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Q. What is the functional group of carboxylic acids?
A.
Amino
B.
Hydroxyl
C.
Carboxyl
D.
Carbonyl
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Solution
Carboxylic acids contain a carboxyl (-COOH) functional group.
Correct Answer: C — Carboxyl
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Q. What is the functional group of esters?
A.
Aldehyde
B.
Carboxyl
C.
Ester
D.
Amine
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Solution
Esters contain the ester functional group, characterized by the structure RCOOR', where R and R' are hydrocarbon chains.
Correct Answer: C — Ester
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Q. What is the functional group present in aldehydes?
A.
-OH
B.
-COOH
C.
-CHO
D.
-NH2
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Solution
Aldehydes contain the -CHO functional group, which is characteristic of this class of compounds.
Correct Answer: C — -CHO
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Q. What is the functional group present in alkenes?
A.
Alcohol
B.
Aldehyde
C.
Alkene
D.
Alkyne
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Solution
The functional group present in alkenes is the alkene group, characterized by a carbon-carbon double bond.
Correct Answer: C — Alkene
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Q. What is the geometry of a molecule with sp hybridization?
A.
Linear
B.
Trigonal planar
C.
Tetrahedral
D.
Bent
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Solution
Molecules with sp hybridization have a linear geometry due to the arrangement of two hybrid orbitals at 180 degrees.
Correct Answer: A — Linear
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Q. What is the geometry of the complex ion [Cu(NH3)4]SO4?
A.
Tetrahedral
B.
Square planar
C.
Octahedral
D.
Trigonal bipyramidal
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Solution
The geometry of [Cu(NH3)4]2+ is square planar due to the presence of a d9 configuration in copper.
Correct Answer: B — Square planar
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Q. What is the Gibbs free energy change (ΔG) at 298 K for a reaction with ΔH = -100 kJ and ΔS = -200 J/K?
A.
-100 kJ
B.
-200 kJ
C.
0 kJ
D.
100 kJ
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Solution
ΔG = ΔH - TΔS = -100,000 J - 298(-200) = -100,000 J + 59,600 J = -40,400 J = -40.4 kJ.
Correct Answer: A — -100 kJ
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Q. What is the half-life of a first-order reaction dependent on?
A.
Initial concentration
B.
Rate constant only
C.
Both initial concentration and rate constant
D.
Temperature only
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Solution
The half-life of a first-order reaction is independent of the initial concentration and depends only on the rate constant k.
Correct Answer: B — Rate constant only
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Q. What is the half-life of a first-order reaction?
A.
Constant and independent of initial concentration
B.
Depends on initial concentration
C.
Increases with time
D.
Decreases with time
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Solution
The half-life of a first-order reaction is constant and independent of the initial concentration of the reactant.
Correct Answer: A — Constant and independent of initial concentration
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Q. What is the hybridization of a molecule with a central atom forming 4 sigma bonds and no lone pairs?
A.
sp
B.
sp2
C.
sp3
D.
dsp3
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Solution
The hybridization is determined by the number of sigma bonds. 4 sigma bonds correspond to sp3 hybridization.
Correct Answer: C — sp3
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Q. What is the hybridization of the carbon atoms in 1-butyne?
A.
sp
B.
sp2
C.
sp3
D.
sp3d
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Solution
In 1-butyne, the carbon atoms involved in the triple bond are sp hybridized.
Correct Answer: A — sp
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Q. What is the hybridization of the central atom in BF3?
A.
sp
B.
sp2
C.
sp3
D.
sp3d
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Solution
The boron atom in BF3 is sp2 hybridized, forming three sigma bonds with fluorine atoms in a trigonal planar arrangement.
Correct Answer: B — sp2
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Q. What is the hybridization of the central atom in methane (CH4)?
A.
sp
B.
sp2
C.
sp3
D.
sp3d
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Solution
The central carbon atom in methane undergoes sp3 hybridization, forming four equivalent sp3 hybrid orbitals.
Correct Answer: C — sp3
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Q. What is the hybridization of the central atom in phosphorus pentachloride (PCl5)?
A.
sp
B.
sp2
C.
sp3
D.
sp3d
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Solution
In PCl5, phosphorus has five bonding pairs and no lone pairs, leading to sp3d hybridization.
Correct Answer: D — sp3d
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Q. What is the hybridization of the central atom in SF4?
A.
sp
B.
sp2
C.
sp3
D.
sp3d
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Solution
The central sulfur atom in SF4 has 4 bonding pairs and 1 lone pair, leading to sp3d hybridization.
Correct Answer: D — sp3d
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Q. What is the hybridization of the central atom in the complex [Ni(CO)4]?
A.
sp
B.
sp2
C.
sp3
D.
d2sp3
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Solution
In [Ni(CO)4], nickel undergoes sp3 hybridization to accommodate four CO ligands.
Correct Answer: C — sp3
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Q. What is the hybridization of the central metal ion in the complex [Ni(CO)4]?
A.
sp
B.
sp2
C.
sp3
D.
d2sp3
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Solution
In [Ni(CO)4], nickel is in the +0 oxidation state and uses sp3 hybridization to form four equivalent bonds with the CO ligands.
Correct Answer: C — sp3
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Q. What is the ideal gas constant (R) value in L·atm/(K·mol)?
A.
0.0821
B.
8.314
C.
62.36
D.
1.987
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Solution
The ideal gas constant R = 0.0821 L·atm/(K·mol) is used in the ideal gas law PV = nRT.
Correct Answer: A — 0.0821
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Q. What is the ideal gas law equation?
A.
PV = nRT
B.
PV = nR
C.
PV = RT
D.
P = nRT/V
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Solution
The ideal gas law is expressed as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.
Correct Answer: A — PV = nRT
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Q. What is the impact of removing a product from a reaction at equilibrium?
A.
Shifts equilibrium to the right
B.
Shifts equilibrium to the left
C.
No effect on equilibrium
D.
Increases the reaction rate
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Solution
Removing a product will shift the equilibrium to the right to produce more product, in accordance with Le Chatelier's Principle.
Correct Answer: A — Shifts equilibrium to the right
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Q. What is the integrated rate law for a second-order reaction?
A.
[A] = [A]0 - kt
B.
1/[A] = 1/[A]0 + kt
C.
[A] = [A]0e^(-kt)
D.
ln[A] = ln[A]0 - kt
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Solution
The integrated rate law for a second-order reaction is given by 1/[A] = 1/[A]0 + kt, where [A]0 is the initial concentration.
Correct Answer: B — 1/[A] = 1/[A]0 + kt
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Q. What is the integrated rate law for a zero-order reaction?
A.
[A] = [A]0 - kt
B.
[A] = [A]0 + kt
C.
[A] = [A]0e^(-kt)
D.
[A] = kt + [A]0
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Solution
For a zero-order reaction, the integrated rate law is [A] = [A]0 - kt, indicating that the concentration decreases linearly with time.
Correct Answer: A — [A] = [A]0 - kt
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Q. What is the ionization energy trend across a period?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Fluctuates
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Solution
Ionization energy generally increases across a period due to increasing nuclear charge.
Correct Answer: A — Increases
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