Q. List two distinguishing features between overloading and short circuiting in domestic
circuits. (CBSE 2014)
ANS-If too many electrical appliances of high power rating are switched on at the same time, they draw an
extremely large current from the circuit causing overloading.
Due to an extremely large current flowing through the circuit, the copper wire of the household wiring
gets heated to a very high temperature and a fire may start.
Short-circuiting:
The touching of naked live wire and neutral wire directly causes short circuiting.
In this case, the resistance of the circuit so formed is very small, thus a large amount of current flows
through the circuit and heats the wires to a high temperature and a fire may start
Q. What is meant by overloading of an electrical circuit? Explain two possible causes due to which
overloading may occur in household circuit? Explain one precaution that should be taken to avoid
the overloading of domestic electric circuit.
ANS- Overloading: The current flowing in domestic wiring at a particular time depends on the power
ratings of the appliances being used. If too many electrical appliances of high power rating are
switched on at the same time, they draw extremely large quantity of current from the circuit.
This is known as the overloading of the circuit.
Due to large current flowing through the wires
of the household circuits, their copper wires get heated up to a very high temperature and can
cause a fire.
Assertion Reason Type Questions Class 11 – Chapter Chemical Equilibrium
Assertion Reason Type Questions Class 11
(a) if both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but the reason is not the correct explanation of the assertion.
(c) If the assertion is true but the reason is false.
(d) If the assertion is false but the reason is true.
1. Assertion: The equilibrium constant is fixed and is the characteristic of any given chemical reaction at a specified temperature. Reason: The composition of the final equilibrium mixture at a particular temperature depends upon the starting amount of reactants. Ans . C
2. Assertion: The endothermic reactions are favoured at lower temperatures and the exothermic reactions are favoured at a higher temperature. Reason: when a system in equilibrium is disturbed by changing the temperature, it will tend to adjust itself so as to overcome the effect of change. Ans . D
3. Assertion: A catalyst does not influence the values of the equilibrium constant. Reason: Catalysts influence the rate of both forward and backward reactions equally. Ans . A
4. Assertion: Kp = Kc for all reactions. Reason: At constant temperature, the pressure of the gas is proportional to its concentration. Ans . D
5. Assertion: The melting point of ice decreases with the increase in pressure.
Reason: Ice contracts on melting. Ans . A
6. Assertion: In dynamic equilibrium, forward and backward reactions continue to take place with equal rates. Reason: In dynamic equilibrium, colour and density change with time. Ans . C
7. Assertion: The equilibrium constant for the reaction. CaSO4. 5H2O (s) ⇌ CaSO4. 3H2O (s) + 2H2O (g) is
Reason: Equilibrium constant is the ratio of the product of the molar concentration of the substances produced to the product of the molar concentrations of reactants with each
concentrations term raised to the power equal to the respective stoichiometric constant. Ans . D
8. Assertion: The gas-phase reaction PCl3(g) + Cl2(g) ⇌ PCl5(g) shifts to the right on increasing pressure. Reason: When pressure increase, equilibrium shifts towards more number of moles. Ans . C
9. Assertion: N2 + 3 H2 ⇌ NH3; ∆H = –92 kJ. High pressure favours the formation of ammonia. Reason: An increase of external pressure on the above reaction at equilibrium favours the reaction in the direction in which the number of moles decreases. Ans . A
10. Assertion: If Qc (reaction quotient) < KC (equilibrium constant) reaction moves in direction of reactants. Reason: The reaction quotient is defined in the same way as the equilibrium constant at any stage of the reaction.
Ans . D
11. Assertion: The physical equilibrium is not static but dynamic in nature. Reason: The physical equilibrium is a state in which two opposing processes are proceeding at the same rate. Ans . A
12. Assertion: Kp = Kc for all reactions. Reason: At constant temperature, the pressure of the gas is proportional to its concentration. Ans : D
13. Assertion: NaCl solution can be purified by the passage of hydrogen chloride through the brine. Reason: his type of purification is based on Le-Chatelier’s principle. Ans . C
14. Assertion: If water is heated to 59°C, the pH will increase. Reason: Kw increases with an increase in temperature. Ans : D
15. Assertion: Ice melts slowly at higher altitudes. Reason: The melting of ice is favoured at high pressure because ice → water shows a decrease in volume. Ans . A
16. Assertion: According to Le-Chatelier’s principle addition of heat to an equilibrium solid ⇌ liquid results in a decrease in the amount of solid. Reason: Reaction is endothermic, so on heating forward reaction is favoured. Ans . B
17. Assertion: The addition of HCl(aq.) to CH3COOH (aq.) decrease the ionisation of CH3COOH (aq.). Reason: Due to the common ion effect H+, ionisation of CH3COOH decreases. Ans . A
18. Assertion: The equilibrium constant for the reverse reaction is the inverse of the equilibrium constant for the reaction in the forwarding direction. Reason: Equilibrium constant depends upon the way in which the reaction is written. Ans . A
19. Assertion: Equilibrium constant has meaning only when the corresponding balanced chemical equation is given. Reason: Its value changes for the new equation obtained by multiplying or dividing the original equation by a number. Ans . A
20. Assertion: The ionisation constants of weak diprotic acid are in the order of Ka1 > Ka2. Reason: Removal of H+ from anion is difficult as compared to neutral atom. Ans : A
1. Read the passage given below and answer the following questions.
Reactants and products coexist at equilibrium, so that the conversion of reactant to products is always less than 100%. Equilibrium reaction may involve the decomposition of a covalent (nonpolar) reactant or ionization of ionic compound into their ions in polar solvents. Ostwald dilution law is the application of the law of mass action to the weak electrolytes in solution. A binary electrolyte AB which dissociates into A+ and B– ions i.e.
for every weak electrolyte, Since α <<1 (1 – α) = 1
(i) A monobasic weak acid solution has a molarity of 0.005 M and pH of 5. What is its percentage ionization in this solution? (a) 2.0 (b) 0.2 (c) 0.5 (d) 0.25
Show Answer(ii) Calculate ionisation constant for pyridinium hydrogen chloride. (Given that H+ ion concentration is 3.6 × 10–4 M and its concentration is 0.02 M.)
(iii) The hydrogen ion concentration of a 10–8 M HCl aqueous solution at 298 K (Kw = 10–14) is (a) 9.525 × 10–8 M (b) 1.0 × 10–8 M (c) 1.0 × 10–6 M (d) 1.0525 × 10–7 M
Show Answer
(iv) Ostwald dilution law is applicable to (a) weak electrolytes (b) non-electrolyte (c) strong electrolyte (d) all type of electrolyte.
Show Answer
(v) If a is the fraction of HI dissociated at equilibrium in the reaction: 2HI ⇔ H2 + I2 then starting with 2 mol of HI, the total number of moles of reactants and products at equilibrium are (a) 1 (b) 2 (c) 1 + α (d) 2 + 2α
2. Read the paragraph and choose correct answer of following questions
Predicting the Direction of the Reaction- The equilibrium constant helps in predicting the direction in which a given reaction will proceed at any stage. For this purpose, we calculate the reaction quotient Q. The reaction quotient, Q (Qc with molar concentrations and QP with partial pressures) is defined in the same way as the equilibrium constant Kc except that the concentrations in Qc are not necessarily equilibrium values. For a general reaction:
a A + b B ⇌ c C + d D
Qc = [C]c [D]d / [A]a [B]b
Relationship between equilibrium constant K, reaction quotient Q and gibbs energy G The value of Kc for a reaction does not depend on the rate of the reaction. However, it is directly related to the thermodynamics of the reaction and in particular, to the change in Gibbs energy, ∆G.
A mathematical expression of this thermodynamic view of equilibrium can be described by the following equation:
∆G = ∆Gø + RT lnQ
where, Gø is standard Gibbs energy. At equilibrium, when ∆G = 0 and Q = Kc , the equation becomes,
∆G = Gø + RT lnK = 0
∆Gø = – RT lnK
lnK = – ∆Gø / RT
Taking antilog of both sides, we get,
K = e–∆G0/RT
i) If … the reaction will proceed in the direction of reactants (reverse reaction).
a) Qc > Kc b) Qc < Kc
c) Qc = Kc d) None of above
ii) If … the reaction will proceed in the direction of the products (forward reaction).
a) Qc > Kc b) Qc < Kc c) Qc = Kc d) None of above
iii) If … the reaction mixture is already at equilibrium. Consider the gaseous reaction.
a) Qc > Kc b) Qc < Kc c) Qc = Kc d) All of above
iv) If ∆G is …. then the reaction is spontaneous and proceeds in the forward direction.
a) zero b) positive c) negative d) None of above
v) ∆G is … reaction has achieved equilibrium; at this point, there is no longer any free energy left to drive the reaction.
