Introduction The period table is the heart of chemistry. Every student studying science encounters it—but many find it overwhelming to memorize. With 118 elements, different groups, periods, and properties, it’s no surprise that it becomes confusing. But what if we told you that you can learn the periodic table on your fingertips ? Yes! This is exactly what the post “Periodic Table on Your Fingertips (2025) (In Hindi)” teaches you, and in this blog post, we break it all down for you in a simple, engaging way. Why Is the Periodic Table Hard to Remember? Students often struggle with: The sheer number of elements Confusing element symbols Remembering the order of elements Understanding group and period arrangements But don’t worry. The solution lies in mnemonics —a memory technique that turns boring facts into fun sentences. What Are Mnemonics? Mnemonics are simple tricks or rhymes that help us remember hard information. Just like we use “My Very Educated Mother Just S...
1.
Question: What happens when the concentration of a reactant is increased in a system at equilibrium?
A) The reaction stops
B) Backward reaction increases
C) Forward reaction increases
D) No change occurs
✓ C) Forward reaction increases
Explanation: According to Le Chatelier’s Principle, when the concentration of a reactant is increased, the system shifts in the direction that consumes the added reactant, which is the forward reaction.
2.
Question: What happens to the equilibrium constant () when the temperature of an exothermic reaction is increased?
A) Increases
B) Decreases
C) Remains the same
D) Becomes zero
✓ B) Decreases
Explanation: In exothermic reactions, heat is a product. Increasing temperature shifts equilibrium towards the reactants, decreasing the concentration of products and therefore decreasing the equilibrium constant ().
3.
Question: What is the effect of a catalyst on a system at equilibrium?
A) Increases the equilibrium constant
B) Decreases the equilibrium constant
C) Speeds up both forward and reverse reactions equally
D) Shifts equilibrium toward products
✓ C) Speeds up both forward and reverse reactions equally
Explanation: A catalyst speeds up the forward and reverse reactions equally, helping the system reach equilibrium faster but does not affect the equilibrium constant or the position of equilibrium.
4.
Question: Which of the following is true for a system at dynamic equilibrium?
A) The forward reaction stops
B) The reverse reaction stops
C) The concentrations of reactants and products remain constant
D) The reaction ceases completely
✓ C) The concentrations of reactants and products remain constant
Explanation: In dynamic equilibrium, both forward and reverse reactions continue at the same rate, so the concentrations of reactants and products remain constant.
5.
Question: If the equilibrium constant () for a reaction is very large, what does this indicate?
A) The reaction strongly favors reactants
B) The reaction strongly favors products
C) The reaction is at equilibrium
D) The reaction has stopped
✓ B) The reaction strongly favors products
Explanation: A large equilibrium constant means that at equilibrium, the concentration of products is much higher than that of reactants, indicating the reaction strongly favors products.
6.
Question: In which type of reaction does the equilibrium constant () decrease when temperature increases?
A) Endothermic
B) Exothermic
C) Reversible
D) Irreversible
✓ B) Exothermic
Explanation: For exothermic reactions, heat is a product. Increasing the temperature shifts equilibrium toward the reactants (backward reaction), reducing the concentration of products and thus decreasing the equilibrium constant.
7.
Question: What happens to the equilibrium position when a reactant is removed from a system at equilibrium?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) Reaction stops
✓ A) Shifts toward reactants
Explanation: Removing a reactant causes the system to shift towards the reactants to replenish the removed substance and restore equilibrium.
8.
Question: What is the equilibrium constant expression for the reaction:
A)
B)
C)
D)
✓ B)
Explanation: The equilibrium constant expression is derived by placing the concentration of products in the numerator and reactants in the denominator. The exponents are equal to the coefficients in the balanced equation.
9.
Question: If the reaction quotient is greater than the equilibrium constant , in which direction will the reaction proceed?
A) Forward
B) Backward
C) No change
D) Reaction stops
✓ B) Backward
Explanation: When , the system has more products than at equilibrium, so the reaction will shift toward the reactants (backward direction) to restore equilibrium.
10.
Question: Which factor does NOT affect the equilibrium position of a reaction?
A) Temperature
B) Concentration
C) Catalyst
D) Pressure
✓ C) Catalyst
Explanation: A catalyst speeds up both the forward and reverse reactions equally, helping the system reach equilibrium faster, but it does not affect the equilibrium position or the equilibrium constant.
11.
Question: What happens to the equilibrium constant when a reaction is reversed?
A) remains the same
B) is squared
C) is inverted (reciprocal)
D) is doubled
✓ C) is inverted (reciprocal)
Explanation: When a reaction is reversed, the equilibrium constant is the reciprocal of the original one. If the original equilibrium constant is , the new equilibrium constant becomes .
12.
Question: If the pressure is increased in a reaction where the number of gas molecules is greater on the reactant side, what happens?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) The reaction stops
✓ B) Shifts toward products
Explanation: According to Le Chatelier’s Principle, when pressure is increased, the equilibrium shifts toward the side with fewer gas molecules to reduce pressure.
13.
Question: What does the equilibrium constant depend on?
A) Pressure
B) Temperature
C) Concentration
D) Volume
✓ B) Temperature
Explanation: The equilibrium constant is dependent on temperature, as changes in temperature can shift the equilibrium position and alter the value of .
14.
Question: If , what does this mean for the system?
A) The reaction is not at equilibrium
B) The reaction is at equilibrium
C) The reaction will shift toward reactants
D) The reaction will stop
✓ B) The reaction is at equilibrium
Explanation: If the reaction quotient equals the equilibrium constant , the system is at equilibrium and no shift will occur.
15.
Question: What happens to the equilibrium constant if the reaction is multiplied by 2?
A) is squared
B) is doubled
C) is halved
D) remains the same
✓ A) is squared
Explanation: If the reaction is multiplied by 2, the equilibrium constant is raised to the power of 2.
16.
Question: What is the effect of increasing the volume of a system at equilibrium where the number of moles of gas is greater on the reactant side?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) The reaction stops
✓ A) Shifts toward reactants
Explanation: Increasing the volume decreases pressure, and the equilibrium will shift toward the side with more gas molecules, which, in this case, is the reactant side.
17.
Question: In which of the following cases will the equilibrium shift to the right?
A) Removing a product
B) Adding a product
C) Removing a reactant
D) Adding a reactant
✓ D) Adding a reactant
Explanation: Adding a reactant to the system will shift the equilibrium toward the products, as the system tries to consume the excess reactant.
18.
Question: Which of the following factors will not change the equilibrium constant () of a reaction?
A) Temperature
B) Pressure
C) Catalyst
D) Concentration
✓ C) Catalyst
Explanation: A catalyst speeds up the rate of a reaction but does not affect the equilibrium constant or the equilibrium position.
19.
Question: In a reaction at equilibrium, which of the following is true?
A) The rate of the forward reaction is greater than the rate of the reverse reaction
B) The rate of the forward reaction is equal to the rate of the reverse reaction
C) The rate of the reverse reaction is greater than the rate of the forward reaction
D) The reaction has stopped
✓ B) The rate of the forward reaction is equal to the rate of the reverse reaction
Explanation: At equilibrium, the rates of the forward and reverse reactions are equal, so the concentrations of reactants and products remain constant.
20.
Question: What is the effect of decreasing the pressure in a system at equilibrium where there are more moles of gas on the product side?
A) Shifts toward products
B) Shifts toward reactants
C) No change
D) The reaction stops
✓ B) Shifts toward reactants
Explanation: Decreasing the pressure favors the side with more gas molecules, so the equilibrium shifts toward the reactants.
21.
Question: What happens to the equilibrium constant when a reaction is divided into two separate steps?
A) is multiplied
B) is added
C) is the average
D) is halved
✓ A) is multiplied
Explanation: When a reaction is divided into two separate steps, the equilibrium constant for the overall reaction is the product of the equilibrium constants for each individual step.
22.
Question: If the number of moles of gas is equal on both sides of the reaction, what happens when pressure is increased?
A) The equilibrium shifts toward the reactants
B) The equilibrium shifts toward the products
C) The equilibrium does not change
D) The reaction stops
✓ C) The equilibrium does not change
Explanation: If the number of gas molecules is equal on both sides of the reaction, increasing the pressure has no effect on the equilibrium position.
23.
Question: What does the reaction quotient tell us?
A) The reaction rate
B) The position of equilibrium
C) The concentration of reactants only
D) The concentration of products only
✓ B) The position of equilibrium
Explanation: The reaction quotient compares the concentrations of products and reactants at any point in the reaction, indicating whether the system is at equilibrium.
24.
Question: What happens if ?
A) The reaction will shift toward the reactants
B) The reaction will shift toward the products
C) The reaction is at equilibrium
D) The reaction will stop
✓ B) The reaction will shift toward the products
Certainly! Here are the remaining MCQs from 25 onwards:
25.
Question: What is the effect of increasing the temperature on an endothermic reaction?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) Reaction stops
✓ B) Shifts toward products
Explanation: In an endothermic reaction, heat is absorbed as a reactant. Increasing the temperature adds more heat, which causes the equilibrium to shift toward the products to absorb the added heat.
26.
Question: Which of the following will NOT affect the equilibrium position of a reaction?
A) Catalyst
B) Concentration of reactants
C) Temperature
D) Pressure
✓ A) Catalyst
Explanation: A catalyst speeds up both the forward and reverse reactions equally and does not affect the equilibrium position.
27.
Question: What happens when the volume of a container is decreased for a reaction where the number of moles of gas is greater on the product side?
A) Shifts toward products
B) Shifts toward reactants
C) No change
D) Reaction stops
✓ B) Shifts toward reactants
Explanation: Decreasing the volume increases the pressure, and according to Le Chatelier’s Principle, the system will shift toward the side with fewer gas molecules, which is the reactant side in this case.
28.
Question: For a reaction at equilibrium, which of the following statements is true?
A) The concentrations of reactants and products are always equal
B) The concentrations of reactants and products remain constant
C) The forward reaction stops
D) The reverse reaction stops
✓ B) The concentrations of reactants and products remain constant
Explanation: At equilibrium, the concentrations of reactants and products remain constant over time, even though both the forward and reverse reactions continue.
29.
Question: In a system at equilibrium, if the concentration of a product is increased, what will happen?
A) The equilibrium shifts toward the reactants
B) The equilibrium shifts toward the products
C) No change
D) The reaction stops
✓ A) The equilibrium shifts toward the reactants
Explanation: Adding more product will disturb the equilibrium, causing the system to shift toward the reactants to reduce the product concentration and restore equilibrium.
30.
Question: Which of the following factors does NOT affect the equilibrium constant for a given reaction?
A) Temperature
B) Pressure
C) Catalyst
D) Concentration
✓ C) Catalyst
Explanation: A catalyst accelerates the rate of reaction but does not affect the equilibrium constant or position.
31.
Question: What is the effect of decreasing the pressure in a system at equilibrium with more moles of gas on the reactant side?
A) Shifts toward products
B) Shifts toward reactants
C) No change
D) The reaction stops
✓ A) Shifts toward products
Explanation: Decreasing pressure favors the side with more gas molecules. Since the reactant side has more gas molecules, the equilibrium shifts toward the products to increase the number of gas molecules.
32.
Question: Which of the following is true about the equilibrium constant () for a reaction in which the number of moles of products is equal to the number of moles of reactants?
A) depends on the volume
B) depends on the pressure
C) remains unaffected by changes in pressure or volume
D) is constant for all temperatures
✓ C) remains unaffected by changes in pressure or volume
Explanation: If the number of moles of gas is the same on both sides, changes in pressure or volume do not affect the equilibrium constant.
33.
Question: If the equilibrium constant for a reaction is 1, what does this imply?
A) The reaction favors the products
B) The reaction favors the reactants
C) The concentrations of products and reactants are equal at equilibrium
D) The reaction does not proceed to equilibrium
✓ C) The concentrations of products and reactants are equal at equilibrium
Explanation: If , the concentrations of products and reactants are equal at equilibrium, indicating that neither side is favored.
34.
Question: Which statement correctly describes the reaction quotient ()?
A) is always equal to
B) is the ratio of products to reactants at equilibrium
C) is the ratio of concentrations at any point in the reaction, not necessarily at equilibrium
D) is always constant
✓ C) is the ratio of concentrations at any point in the reaction, not necessarily at equilibrium
Explanation: is the ratio of the concentrations of products to reactants at any point in the reaction. When , the system is at equilibrium.
35.
Question: Which of the following changes will shift the equilibrium to the left in an exothermic reaction?
A) Increasing temperature
B) Adding a catalyst
C) Removing a reactant
D) Increasing pressure
✓ A) Increasing temperature
Explanation: Increasing the temperature in an exothermic reaction adds heat to the system, and the equilibrium shifts toward the reactants (left) to absorb the excess heat.
36.
Question: What does it mean if for a reaction?
A) The reaction strongly favors products
B) The reaction strongly favors reactants
C) The reaction is at equilibrium
D) The reaction is irreversible
✓ A) The reaction strongly favors products
Explanation: A large value of (such as ) indicates that at equilibrium, the concentration of products is much higher than that of reactants, meaning the reaction strongly favors products.
37.
Question: What is the effect of adding an inert gas to a system at equilibrium?
A) Shifts the equilibrium toward the products
B) Shifts the equilibrium toward the reactants
C) No effect on the equilibrium position
D) Stops the reaction
✓ C) No effect on the equilibrium position
Explanation: Adding an inert gas does not affect the partial pressures of the reacting gases, so it does not change the equilibrium position.
38.
Question: Which of the following is a correct statement about equilibrium?
A) Equilibrium is always reached when the reaction is completed
B) At equilibrium, the concentrations of reactants and products are always equal
C) At equilibrium, the forward and reverse reactions occur at the same rate
D) At equilibrium, the concentrations of reactants and products continuously change
✓ C) At equilibrium, the forward and reverse reactions occur at the same rate
Explanation: At equilibrium, the forward and reverse reactions occur at the same rate, which results in constant concentrations of reactants and products.
39.
Question: What is the effect of increasing the concentration of a reactant in a system at equilibrium?
A) Shifts the equilibrium to the right
B) Shifts the equilibrium to the left
C) No effect on the equilibrium
D) Stops the reaction
✓ A) Shifts the equilibrium to the right
Explanation: Increasing the concentration of a reactant shifts the equilibrium toward the products (right) to consume the added reactant and restore balance.
40.
Question: If the equilibrium constant for a reaction is less than 1, what does this indicate?
A) The reaction strongly favors the reactants
B) The reaction strongly favors the products
C) The reaction has reached completion
D) The concentrations of reactants and products are equal at equilibrium
✓ A) The reaction strongly favors the reactants
Explanation: If is less than 1, it means that at equilibrium, the concentration of reactants is much higher than that of products, indicating that the reaction favors the reactants.
41.
Question: What happens when the volume of a gas reaction container is increased, and the number of moles of gas is greater on the reactant side?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) The reaction stops
✓ B) Shifts toward products
Explanation: Increasing the volume decreases the pressure, and the equilibrium shifts toward the side with more gas molecules to balance the pressure, which in this case is the product side.
42.
Question: How does increasing the concentration of a product affect a reaction at equilibrium?
A) Shifts equilibrium toward reactants
B) Shifts equilibrium toward products
C) No effect
D) Stops the reaction
✓ A) Shifts equilibrium toward reactants
Explanation: Adding a product will disturb the equilibrium, causing the system to shift toward the reactants to reduce the product concentration.
43.
Question: If a reaction is endothermic and the temperature is decreased, what will happen?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) The reaction stops
✓ A) Shifts toward reactants
Explanation: For endothermic reactions, decreasing temperature removes heat, and the equilibrium shifts toward the reactants to absorb heat.
44.
Question: What is the equilibrium constant for the reaction:
A)
B)
C)
D)
✓ A)
Explanation: The equilibrium constant expression is written in terms of the concentration of products over reactants, each raised to the power of their coefficients in the balanced chemical equation.
45.
Question: What happens when a system at equilibrium is disturbed by adding more reactant?
A) The equilibrium shifts toward the products
B) The equilibrium shifts toward the reactants
C) The equilibrium remains unchanged
D) The reaction stops
✓ A) The equilibrium shifts toward the products
Explanation: Adding more reactant increases its concentration, and the equilibrium shifts toward the products to reduce the concentration of the reactants.
46.
Question: What is the effect of increasing the pressure on a reaction where the number of moles of gas is greater on the product side?
A) Shifts toward the reactants
B) Shifts toward the products
C) No change
D) The reaction stops
✓ A) Shifts toward the reactants
Explanation: Increasing the pressure will shift the equilibrium toward the side with fewer moles of gas, which is the reactant side in this case.
47.
Question: The equilibrium constant of a reaction is 10^(-3). What does this indicate about the reaction?
A) The products are favored
B) The reactants are favored
C) The reaction reaches completion
D) The equilibrium concentration of products is equal to that of reactants
✓ B) The reactants are favored
Explanation: A small value of indicates that, at equilibrium, the concentration of reactants is much higher than that of products, meaning the reactants are favored.
48.
Question: What effect does a decrease in the temperature of an exothermic reaction have on the equilibrium?
A) Shifts toward the products
B) Shifts toward the reactants
C) No effect
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: Decreasing the temperature in an exothermic reaction removes heat, and the equilibrium shifts toward the reactants to produce more heat.
49.
Question: Which of the following is true about a system at equilibrium?
A) The forward and reverse reactions occur at different rates
B) The concentration of reactants and products changes over time
C) The forward and reverse reactions occur at the same rate
D) The system will always favor the reactants
✓ C) The forward and reverse reactions occur at the same rate
Explanation: At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction, which results in constant concentrations of reactants and products.
50.
Question: What will happen if the concentration of a reactant is decreased in a system at equilibrium?
A) The equilibrium shifts toward the products
B) The equilibrium shifts toward the reactants
C) No effect on the equilibrium
D) The reaction stops
✓ B) The equilibrium shifts toward the reactants
Explanation: Decreasing the concentration of a reactant disturbs the equilibrium, and the system will shift toward the reactants to replenish the lost reactant.
51.
Question: If the equilibrium constant for a reaction is very large, what does this indicate?
A) The products are favored
B) The reactants are favored
C) The reaction does not proceed
D) The equilibrium is at the midpoint
✓ A) The products are favored
Explanation: A large equilibrium constant indicates that, at equilibrium, the concentration of products is much higher than that of reactants, meaning the products are favored.
52.
Question: What does the reaction quotient (Q) represent?
A) The ratio of products to reactants at equilibrium
B) The ratio of products to reactants at any point during the reaction
C) The concentration of only products
D) The concentration of only reactants
✓ B) The ratio of products to reactants at any point during the reaction
Explanation: The reaction quotient, , represents the ratio of the concentrations of products to reactants at any point in time, not necessarily at equilibrium.
53.
Question: For a reaction , what is the correct expression for the equilibrium constant?
A)
B)
C)
D)
✓ A)
Explanation: The equilibrium constant expression is written as the ratio of the concentrations of products (raised to their respective coefficients) to the concentrations of reactants (raised to their respective coefficients).
54.
Question: What happens when a system at equilibrium is disturbed by increasing the pressure?
A) The equilibrium shifts to the side with fewer gas molecules
B) The equilibrium shifts to the side with more gas molecules
C) The equilibrium remains unchanged
D) The reaction stops
✓ A) The equilibrium shifts to the side with fewer gas molecules
Explanation: Increasing the pressure shifts the equilibrium toward the side with fewer gas molecules in order to counteract the pressure increase.
55.
Question: In a reaction, if the concentration of the products is increased, what will happen to the equilibrium?
A) Shifts toward the products
B) Shifts toward the reactants
C) No change
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: Increasing the concentration of products disturbs the equilibrium, causing the system to shift toward the reactants to reduce the product concentration.
56.
Question: What is the effect of increasing the temperature on an exothermic reaction?
A) Shifts toward reactants
B) Shifts toward products
C) No effect
D) The reaction stops
✓ A) Shifts toward reactants
Explanation: In an exothermic reaction, heat is released as a product. Increasing the temperature adds more heat, and the equilibrium shifts toward the reactants to absorb the added heat.
57.
Question: Which of the following will not affect the equilibrium constant ()?
A) Temperature
B) Pressure
C) Volume
D) Concentration
✓ D) Concentration
Explanation: Changes in concentration will affect the equilibrium position but not the equilibrium constant. is only affected by temperature.
58.
Question: Which of the following statements is true for a system at equilibrium?
A) The rate of the forward reaction is equal to the rate of the reverse reaction
B) The concentrations of reactants and products are equal
C) The forward reaction has stopped
D) The reverse reaction has stopped
✓ A) The rate of the forward reaction is equal to the rate of the reverse reaction
Explanation: At equilibrium, the forward and reverse reactions continue to occur, but at the same rate, so the concentrations of reactants and products remain constant.
59.
Question: What happens to the equilibrium constant if the temperature of the reaction is increased for an endothermic reaction?
A) The equilibrium constant decreases
B) The equilibrium constant increases
C) The equilibrium constant remains the same
D) The equilibrium constant becomes zero
✓ B) The equilibrium constant increases
Explanation: For an endothermic reaction, increasing temperature adds heat, and the equilibrium constant increases as the reaction favors the production of more products at higher temperatures.
60.
Question: For the reaction , what is the effect of increasing the pressure?
A) Shifts toward products
B) Shifts toward reactants
C) No change
D) The reaction stops
✓ A) Shifts toward products
Explanation: Increasing the pressure shifts the equilibrium toward the side with fewer gas molecules. In this case, the product side has fewer moles of gas, so the equilibrium shifts toward the products.
61.
Question: The reaction quotient is greater than the equilibrium constant . What does this indicate?
A) The system is at equilibrium
B) The system will shift toward the products
C) The system will shift toward the reactants
D) The reaction will stop
✓ C) The system will shift toward the reactants
Explanation: If , it means there are too many products compared to reactants, and the system will shift toward the reactants to restore equilibrium.
62.
Question: What is the impact of a catalyst on the equilibrium of a reaction?
A) It increases the concentration of products at equilibrium
B) It decreases the concentration of products at equilibrium
C) It has no effect on the equilibrium position
D) It makes the reaction irreversible
✓ C) It has no effect on the equilibrium position
Explanation: A catalyst speeds up both the forward and reverse reactions equally, allowing the system to reach equilibrium more quickly, but it does not affect the equilibrium position.
63.
Question: What will happen to the equilibrium if the volume of the container is decreased in a system with more moles of gas on the product side?
A) Shifts toward reactants
B) Shifts toward products
C) No change
D) The reaction stops
✓ A) Shifts toward reactants
Explanation: Decreasing the volume increases the pressure, and the equilibrium will shift toward the side with fewer gas molecules (the reactant side in this case) to reduce the pressure.
64.
Question: What happens when the temperature is increased in an exothermic reaction?
A) Shifts toward the products
B) Shifts toward the reactants
C) No change
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: For exothermic reactions, increasing temperature adds heat, and the equilibrium shifts toward the reactants to absorb the added heat.
65.
Question: What is the effect of adding a solvent to a system at equilibrium?
A) Shifts the equilibrium to the left
B) Shifts the equilibrium to the right
C) No effect if the solvent doesn't participate in the reaction
D) The reaction stops
✓ C) No effect if the solvent doesn't participate in the reaction
Explanation: If the solvent does not participate in the reaction, adding more solvent does not affect the equilibrium position, as it only dilutes the reactants and products uniformly.
Here’s the continuation from question 66 onward:
66.
Question: If the concentration of a product is increased, what will happen to the equilibrium?
A) Shifts toward the products
B) Shifts toward the reactants
C) No change
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: Increasing the concentration of a product will disturb the equilibrium, causing the system to shift toward the reactants to reduce the product concentration.
67.
Question: For the reaction:
What happens when the temperature is increased?
A) Shifts toward the products
B) Shifts toward the reactants
C) No change
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: The reaction is exothermic, and increasing temperature adds heat, causing the equilibrium to shift toward the reactants to absorb the excess heat.
68.
Question: Which of the following does NOT change the value of the equilibrium constant ()?
A) Temperature
B) Pressure
C) Concentration
D) Volume
✓ B) Pressure
Explanation: The equilibrium constant is only affected by temperature. Changes in pressure, concentration, or volume affect the position of equilibrium but not the constant itself.
69.
Question: The equilibrium constant expression for the reaction
is given by:
A)
B)
C)
D)
✓ B)
Explanation: The equilibrium constant expression is written in terms of the products over the reactants, raised to the power of their coefficients in the balanced equation.
70.
Question: In a chemical reaction, the reaction quotient is less than the equilibrium constant . What does this indicate?
A) The system is at equilibrium
B) The system will shift toward the products
C) The system will shift toward the reactants
D) The reaction will stop
✓ B) The system will shift toward the products
Explanation: If , it means the concentration of products is too low compared to the reactants, and the equilibrium will shift toward the products to reach equilibrium.
71.
Question: In an exothermic reaction, increasing the temperature will:
A) Increase the concentration of reactants
B) Increase the concentration of products
C) No effect on the equilibrium
D) Shift the equilibrium toward the reactants
✓ D) Shift the equilibrium toward the reactants
Explanation: In exothermic reactions, increasing temperature adds heat, causing the equilibrium to shift toward the reactants to absorb the added heat.
72.
Question: For the reaction:
If the concentration of reactant A is decreased, what happens to the equilibrium?
A) Shifts toward the products
B) Shifts toward the reactants
C) No change
D) The reaction stops
✓ A) Shifts toward the products
Explanation: If the concentration of reactant A is decreased, the equilibrium will shift toward the side that produces more A to counteract the disturbance.
73.
Question: What is the effect of decreasing the temperature in an endothermic reaction?
A) Shifts toward the products
B) Shifts toward the reactants
C) No effect
D) The reaction stops
✓ B) Shifts toward the reactants
Explanation: In an endothermic reaction, decreasing the temperature removes heat, causing the equilibrium to shift toward the reactants to produce more heat.
74.
Question: Which of the following factors does NOT affect the equilibrium position of a reaction?
A) Concentration
B) Temperature
C) Volume
D) The presence of a catalyst
✓ D) The presence of a catalyst
Explanation: A catalyst speeds up the rate at which equilibrium is reached but does not affect the position of equilibrium.
75.
Question: What is the effect of adding a noble gas (which does not react) to a system at equilibrium?
A) Shifts the equilibrium toward the products
B) Shifts the equilibrium toward the reactants
C) No effect on the equilibrium
D) The reaction stops
✓ C) No effect on the equilibrium
Explanation: Adding an inert gas does not change the partial pressures of the reactants or products, so it has no effect on the equilibrium position.
76.
Question: If a reaction is at equilibrium, what can be said about the forward and reverse reactions?
A) The forward reaction is faster than the reverse reaction
B) The reverse reaction is faster than the forward reaction
C) The rates of the forward and reverse reactions are equal
D) Both reactions stop
✓ C) The rates of the forward and reverse reactions are equal
Explanation: At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction, meaning the concentrations of reactants and products remain constant.
77.
Question: In a reaction where the number of moles of gas is equal on both sides, increasing the pressure will:
A) Shift the equilibrium toward the products
B) Shift the equilibrium toward the reactants
C) Have no effect on the equilibrium
D) Stop the reaction
✓ C) Have no effect on the equilibrium
Explanation: If the number of moles of gas is the same on both sides of the reaction, changing the pressure will have no effect on the equilibrium position.
78.
Question: The equilibrium constant for the reaction
is . If the temperature is increased, what will happen to ?
A) will increase if the reaction is exothermic
B) will increase if the reaction is endothermic
C) will decrease if the reaction is endothermic
D) will remain constant
✓ B) will increase if the reaction is endothermic
Explanation: For endothermic reactions, increasing the temperature adds heat, and the equilibrium constant increases as the reaction shifts toward the products.
79.
Question: If a catalyst is added to a system at equilibrium, what will be the result?
A) The reaction will stop
B) The equilibrium constant will change
C) The equilibrium will shift toward the products
D) The reaction will reach equilibrium faster
✓ D) The reaction will reach equilibrium faster
Explanation: A catalyst speeds up both the forward and reverse reactions equally, helping the system reach equilibrium faster, but it does not change the equilibrium position.
80.
Question: What happens when the volume of a gas reaction mixture is increased at constant temperature?
A) The equilibrium will shift toward the side with more gas molecules
B) The equilibrium will shift toward the side with fewer gas molecules
C) The equilibrium will remain the same
D) The reaction will stop
✓ A) The equilibrium will shift toward the side with more gas molecules
Explanation: Increasing the volume of the container lowers the pressure, and the equilibrium will shift toward the side with more gas molecules to counteract the pressure decrease.
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