Q. In a potentiometer, what is the role of the jockey?
A.
To measure current.
B.
To connect the circuit.
C.
To find the balance point.
D.
To provide a reference voltage.
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Solution
The jockey is used to find the balance point where the potential difference is equal to the reference voltage.
Correct Answer: C — To find the balance point.
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Q. In a practical Wheatstone bridge, what is the effect of temperature on resistance measurements?
A.
Temperature has no effect
B.
Resistance increases with temperature
C.
Resistance decreases with temperature
D.
It depends on the material
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Solution
The effect of temperature on resistance measurements in a Wheatstone bridge depends on the material of the resistors, as different materials have different temperature coefficients.
Correct Answer: D — It depends on the material
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Q. In a practical Wheatstone bridge, what is the effect of temperature on the resistors?
A.
It has no effect
B.
It can change resistance values
C.
It only affects the galvanometer
D.
It only affects the power supply
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Solution
Temperature changes can affect the resistance values of the resistors, thus affecting the balance condition.
Correct Answer: B — It can change resistance values
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Q. In a practical Wheatstone bridge, what is the effect of temperature on the resistances?
A.
Resistances remain constant
B.
Resistances increase with temperature
C.
Resistances decrease with temperature
D.
Temperature has no effect
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Solution
In general, the resistance of conductors increases with temperature due to increased atomic vibrations.
Correct Answer: B — Resistances increase with temperature
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Q. In a practical Wheatstone bridge, what is the main source of error?
A.
Temperature variations
B.
Resistance of the connecting wires
C.
Calibration of the galvanometer
D.
Non-ideal resistors
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Solution
Non-ideal resistors can introduce errors in the measurements due to their tolerance and temperature coefficients.
Correct Answer: D — Non-ideal resistors
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Q. In a prism, if the angle of incidence is equal to the angle of emergence, what can be said about the angle of deviation?
A.
It is zero
B.
It is equal to the angle of incidence
C.
It is equal to the angle of emergence
D.
It is equal to the angle of the prism
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Solution
When the angle of incidence equals the angle of emergence, the angle of deviation is equal to the angle of the prism.
Correct Answer: D — It is equal to the angle of the prism
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Q. In a prism, if the angle of the prism is 60 degrees, what is the minimum angle of deviation for light passing through it?
A.
30 degrees
B.
60 degrees
C.
90 degrees
D.
45 degrees
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Solution
The minimum angle of deviation (D) for a prism is given by D = A, where A is the angle of the prism. Therefore, for a 60-degree prism, the minimum angle of deviation is 30 degrees.
Correct Answer: A — 30 degrees
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Q. In a process where 100 J of heat is added to a system and the internal energy increases by 40 J, how much work is done by the system?
A.
60 J
B.
40 J
C.
100 J
D.
140 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W, we have 40 J = 100 J - W, thus W = 100 J - 40 J = 60 J.
Correct Answer: A — 60 J
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Q. In a process where 300 J of heat is added to a system and the internal energy increases by 100 J, how much work is done by the system?
A.
200 J
B.
100 J
C.
300 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W. Rearranging gives W = Q - ΔU. Here, W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a process where 300 J of heat is added to a system and the system does 100 J of work, what is the internal energy change?
A.
200 J
B.
300 J
C.
100 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a process where 300 J of heat is added to a system and the system does 100 J of work, what is the change in internal energy?
A.
200 J
B.
100 J
C.
300 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a reaction A → B, if the concentration of A decreases from 0.5 M to 0.1 M in 20 minutes, what is the average rate of reaction?
A.
0.02 M/min
B.
0.04 M/min
C.
0.05 M/min
D.
0.06 M/min
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Solution
Average rate = (change in concentration) / (time) = (0.5 - 0.1) / 20 = 0.02 M/min.
Correct Answer: B — 0.04 M/min
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Q. In a reaction A → B, if the rate of formation of B is 0.1 mol/L·s, what is the rate of disappearance of A?
A.
0.1 mol/L·s
B.
0.05 mol/L·s
C.
0.2 mol/L·s
D.
0.1 L/mol·s
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Solution
For the reaction A → B, the rate of disappearance of A is equal to the rate of formation of B, hence it is 0.1 mol/L·s. However, if stoichiometry is considered as 1:1, the rate of disappearance of A is also 0.1 mol/L·s.
Correct Answer: C — 0.2 mol/L·s
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Q. In a reaction A → B, if the rate of formation of B is 0.5 mol/L·s, what is the rate of disappearance of A?
A.
0.5 mol/L·s
B.
1.0 mol/L·s
C.
0.25 mol/L·s
D.
0.75 mol/L·s
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Solution
For the reaction A → B, the rate of disappearance of A is equal to the rate of formation of B, thus it is 1.0 mol/L·s.
Correct Answer: B — 1.0 mol/L·s
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Q. In a reaction A → B, if the rate of reaction doubles when the concentration of A is doubled, what is the order of the reaction with respect to A?
A.
Zero order
B.
First order
C.
Second order
D.
Third order
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Solution
If the rate doubles when the concentration of A is doubled, the reaction is first order with respect to A.
Correct Answer: B — First order
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Q. In a reaction at equilibrium, if the concentration of a reactant is decreased, what will happen?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase the rate of reaction
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Solution
According to Le Chatelier's principle, decreasing the concentration of a reactant will shift the equilibrium to the left to produce more reactants.
Correct Answer: B — Shift to the left
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Q. In a reaction at equilibrium, if the concentration of products increases, what will happen to the equilibrium position?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on temperature
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Solution
According to Le Chatelier's principle, if the concentration of products increases, the equilibrium will shift to the left.
Correct Answer: A — Shift to the left
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Q. In a reaction at equilibrium, if the concentration of products is decreased, what will happen?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the temperature
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Solution
Decreasing the concentration of products will shift the equilibrium to the right to produce more products, according to Le Chatelier's principle.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the equilibrium position?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the reaction
Show solution
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to produce more products.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the equilibrium?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Equilibrium constant increases
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Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium to the right to form more products.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the temperature is decreased, what will happen to the equilibrium position if the reaction is exothermic?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the concentration
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Solution
For an exothermic reaction, decreasing the temperature shifts the equilibrium to the right, favoring the formation of products.
Correct Answer: A — Shift to the right
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Q. In a reaction at equilibrium, if the temperature is increased and the reaction is exothermic, what will happen to the equilibrium position?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Equilibrium constant increases
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Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium position to the left, favoring the reactants.
Correct Answer: B — Shift to the left
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Q. In a reaction at equilibrium, if the temperature is increased, what will happen to the equilibrium constant Kc for an endothermic reaction?
A.
Increase
B.
Decrease
C.
No change
D.
Depends on concentration
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Solution
For an endothermic reaction, increasing temperature shifts the equilibrium to the right, increasing Kc.
Correct Answer: A — Increase
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Q. In a reaction mechanism, the slowest step is known as the:
A.
Rate-determining step
B.
Intermediate step
C.
Fast step
D.
Catalytic step
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Solution
The slowest step in a reaction mechanism is called the rate-determining step, as it controls the overall reaction rate.
Correct Answer: A — Rate-determining step
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Q. In a reaction mechanism, the slowest step is known as what?
A.
Rate-determining step
B.
Intermediate step
C.
Fast step
D.
Catalytic step
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Solution
The slowest step in a reaction mechanism is known as the rate-determining step.
Correct Answer: A — Rate-determining step
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Q. In a reaction where 2 moles of hydrogen react with 1 mole of oxygen, how many moles of water are produced?
A.
1 mole
B.
2 moles
C.
3 moles
D.
4 moles
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Solution
According to the balanced equation 2H2 + O2 → 2H2O, 2 moles of H2 produce 2 moles of H2O.
Correct Answer: B — 2 moles
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Q. In a reaction where ΔH is negative and ΔS is positive, what can be said about ΔG?
A.
ΔG is always negative.
B.
ΔG is always positive.
C.
ΔG is zero.
D.
ΔG depends on temperature.
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Solution
If ΔH is negative and ΔS is positive, ΔG will always be negative at all temperatures.
Correct Answer: A — ΔG is always negative.
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Q. In a reaction where ΔH is positive and ΔS is negative, what is the sign of ΔG at high temperatures?
A.
Positive
B.
Negative
C.
Zero
D.
Cannot be determined
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Solution
At high temperatures, ΔG will be positive because the positive ΔH and negative ΔS will dominate the equation ΔG = ΔH - TΔS.
Correct Answer: A — Positive
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Q. In a reaction, 3 moles of A react with 2 moles of B to produce 4 moles of C. What is the mole ratio of A to C?
A.
3:4
B.
2:3
C.
4:3
D.
1:1
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Solution
The mole ratio of A to C is 3:4 based on the coefficients in the balanced equation.
Correct Answer: A — 3:4
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Q. In a reaction, if the enthalpy change (ΔH) is -100 kJ and the entropy change (ΔS) is 200 J/K, what is the Gibbs free energy change (ΔG) at 298 K?
A.
-100 kJ
B.
-50 kJ
C.
0 kJ
D.
50 kJ
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Solution
ΔG = ΔH - TΔS = -100 kJ - (298 K * 0.2 kJ/K) = -100 kJ - 59.6 kJ = -159.6 kJ.
Correct Answer: A — -100 kJ
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