Free NEET Chemistry multiple-choice questions on Le Chatelier's Principle. Attempt each question and reveal the answer with a full explanation.
According to Le Chatelier's principle, adding heat to a solid-liquid equilibrium will cause the: Amount of liquid to increase Amount of solid to increase Temperature to increase Temperature to decrease Which one of the following conditions will favour maximum formation of the product in the reaction, A2(g) + B2(g) <=> X2(g) r H = -X kJ ? High temperature and high pressure Low temperature and low pressure Low temperature and high pressure High temperature and low pressure Which of the following conditions will favour maximum formation of the product in the reaction: A 2(g) + B 2(g) X 2(g) , r H = -X kJ ? Low temperature and high pressure High temperature and high pressure Low temperature and low pressure High temperature and low pressure Which of the following will not affect the state of equilibrium for the reaction N 2(g) + O 2(g) 2NO(g) ? Increase in pressure Increase in temperature Addition of N 2 Removal of NO Addition of an inert gas to the equilibrium system PCl 5(g) PCl 3(g) + Cl 2(g) at constant volume: Does not affect the equilibrium Increases the dissociation of PCl 5 Decreases the dissociation of PCl 5 Increases the concentration of PCl 5 The reaction C(s) + H 2O(g) CO(g) + H 2(g) is in equilibrium. Which of the following will shift the equilibrium to the right? Decreasing the pressure Increasing the pressure Adding a catalyst Decreasing the volume of the container For a reversible reaction, if the temperature is increased, the value of the equilibrium constant K : Increases if H is positive Decreases if H is positive Increases if H is negative Remains constant regardless of H The value of the ionic product of water ( K w ) increases with an increase in temperature because: The ionization of water is an endothermic process. The ionization of water is an exothermic process. Density of water decreases with temperature. Water becomes more acidic at higher temperatures. For the reaction N 2(g) + O 2(g) 2NO(g) , H = 180.5 kJ . Which factor will favor the formation of NO ? Increase in temperature Increase in pressure Decrease in temperature Decrease in volume In the reaction A + B C + D , the value of equilibrium constant K is 100 at 25 C and 200 at 50 C . The reaction is: Endothermic Exothermic Unpredictable At equilibrium Which of the following conditions favors the dissociation of PCl 5 according to the reaction: PCl 5(g) PCl 3(g) + Cl 2(g) , H = +92.5 kJ ? High temperature and Low pressure Low temperature and High pressure High temperature and High pressure Low temperature and Low pressure For the equilibrium C(s) + CO 2(g) 2CO(g) , the addition of more graphite ( C(s) ) at constant temperature and volume will: Not affect the equilibrium Shift the equilibrium to the right Shift the equilibrium to the left Decrease the concentration of CO The addition of an inert gas at constant pressure to the system N 2(g) + 3H 2(g) 2NH 3(g) will: Shift the equilibrium to the left Shift the equilibrium to the right Have no effect Increase the concentration of NH 3 Applying Le Chatelier's principle to the equilibrium: Ice Water , an increase in pressure will: Lower the melting point of ice Increase the melting point of ice Have no effect on the equilibrium Convert all water to ice For the reaction 2NO 2 (g) N 2 O 4 (g) , if the volume of the container is increased at constant temperature, the equilibrium will: Shift to the left Shift to the right Remain unchanged Cause K p to increase For the equilibrium reaction PCl 5(g) PCl 3(g) + Cl 2(g) , what is the effect of adding an inert gas at constant pressure? The equilibrium shifts in the forward direction. The equilibrium shifts in the backward direction. The equilibrium remains unaffected. The concentration of PCl 5 increases. For the equilibrium Ice Water , which of the following is correct? High pressure favors the forward reaction. High pressure favors the backward reaction. Low pressure favors the forward reaction. Temperature does not affect equilibrium. For the reaction 2A(g) B(g) + 3C(g) , the initial pressure of A is P . At equilibrium, the total pressure is 1.5 P . The degree of dissociation of A is: 0.50 0.25 0.75 1.00 Which of the following statements is FALSE regarding the effect of an inert gas on equilibrium? Adding an inert gas at constant volume shifts the equilibrium towards more moles of gas. Adding an inert gas at constant pressure shifts the equilibrium towards the side with more gaseous moles. Adding an inert gas at constant volume has no effect on the state of equilibrium. The addition of an inert gas does not change the value of K c or K p at constant temperature. In the reaction PCl 5(g) PCl 3(g) + Cl 2(g) , H = +92.5 kJ mol -1 . Which of the following conditions will shift the equilibrium to the left? Decreasing the temperature Increasing the volume of the container Adding PCl 5 gas Decreasing the pressure For an endothermic reaction, increasing the temperature will: Increase the value of the equilibrium constant Decrease the value of the equilibrium constant Not change the equilibrium constant Shift equilibrium to the left For the equilibrium 2C(s) + O 2(g) 2CO(g) , if the volume of the vessel is reduced to half, the equilibrium will: Shift to the left Shift to the right Not change Stop For the reaction N 2(g) + 3H 2(g) 2NH 3(g) , H = -92.4 kJ . According to Le Chatelier's principle, the yield of ammonia can be increased by: Increasing pressure and decreasing temperature Decreasing pressure and increasing temperature Increasing both pressure and temperature Decreasing both pressure and temperature The reaction PCl 5(g) PCl 3(g) + Cl 2(g) is in equilibrium at a certain temperature. If the volume of the container is suddenly doubled at constant temperature, then: The degree of dissociation will increase. The value of K c will decrease. The degree of dissociation will decrease. The pressure will remain constant. The dissociation of N 2O 4 is an endothermic process: N 2O 4(g) 2NO 2(g) , H > 0 . Which of the following conditions will result in the highest concentration of NO 2 at equilibrium? High temperature and low pressure Low temperature and high pressure High temperature and high pressure Low temperature and low pressure In the dissociation of N 2O 4(g) 2NO 2(g) , the relationship between the degree of dissociation and the vapour densities ( D for initial, d for equilibrium) is: = D - d d = d - D d = D - d D = D D - d Which factor will shift the equilibrium of the endothermic reaction 2HI(g) H 2(g) + I 2(g) to the right? Increasing the temperature Increasing the pressure Adding a catalyst Decreasing the volume For a given exothermic reaction, K p and K p' are the equilibrium constants at temperatures T 1 and T 2 , respectively. Assuming that heat of reaction is constant in temperature range between T 1 and T 2 , it is readily observed that :- K p > K p' K p < K p' K p = K p' K p = 1 K p' Higher yield of NO in N2(g) + O2(g) <=> 2NO(g) can be obtained at [ H of the reaction = +180.7 kJ mol -1 ] A. Higher temperature B. Lower temperature C. Higher concentration of N2 D. Higher concentration of O2 Choose the correct answer from the options given below : A, C, D only A, D only B, C only B, C, D only Which of the following statements is correct regarding the addition of a catalyst to a system in equilibrium? It decreases the time required to reach equilibrium. It increases the value of the equilibrium constant. It shifts the equilibrium toward the products. It increases the rate of the forward reaction only. In which of the following reactions, will an increase in pressure NOT result in a shift of the equilibrium? H 2(g) + I 2(g) 2HI(g) N 2(g) + 3H 2(g) 2NH 3(g) PCl 5(g) PCl 3(g) + Cl 2(g) 2SO 2(g) + O 2(g) 2SO 3(g) Adding Cl 2 gas to the equilibrium PCl 5 (g) PCl 3 (g) + Cl 2 (g) at constant volume will: Increase the concentration of PCl 5 Increase the concentration of PCl 3 Decrease the pressure Increase the value of K c Which of the following factors will shift the equilibrium N 2(g) + 3H 2(g) 2NH 3(g) to the left? Decreasing the pressure Increasing the pressure Increasing the concentration of H 2 Decreasing the temperature For which of the following reactions will the addition of an inert gas at constant volume have no effect on the equilibrium position? All of these PCl 5(g) PCl 3(g) + Cl 2(g) N 2(g) + 3H 2(g) 2NH 3(g) 2SO 2(g) + O 2(g) 2SO 3(g) Consider the following reaction for which the change in enthalpy is positive 2A(g) + B(g) <=> C(g) + D(g) Which of the following will not affect the equilibrium ? Presence of catalyst Change in concentration of reactants Change in pressure Change in temperature