distinguishing features between overloading and short circuiting in domestic circuits

 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

Overloading of an electrical circuit

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.

CLASS XII PHYSICS IMPORTANT QUESTIONS

Assertion-reason type questions for Equilibrium

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: K_p = K_c 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 Q_c (reaction quotient) < K_C (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: K_p = K_c 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: K_w 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

CBSE CHEMISTRY SAMPLE Question Paper 2023-24 set- I

REASONING QUESTIONS ORGANIC CHEMISTRY

1.     Before nitration aniline is converted into acetanilide

2.     Aryl halides can not be prepared by the reaction of  phenol with hydrogen halides.

3.     Sulphuric acid is not used during the reaction of alcohols with KI.

4.     The haloalkanes are only very slightly soluble in water

5.     Haloalkanes react with KCN to form alkyl cyanides as main product while AgCN forms isocyanides as the chief product.

6.     Although chlorine is an electron withdrawing group, yet it is ortho-, para- directing in electrophilic aromatic substitution reactions.

7.     The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

8.     Grignard reagents should be prepared under anhydrous conditions.

9.     p-dichlorobenzene has higher melting point than those of o- and m- isomers.

10.  COH bond angle in alcohols is slightly less than the tetrahedral angle.

11.  The C-O bond length in phenol is slightly less than that in methanol.

12.  Tertiary alcohols do not under go oxidation reaction.

13.  Ortho and para nitrophenols are more acidic than phenols.

14.  Bimolecular dehydration of alcohols is not appropriate for the preparation of ethyl methyl ether.

15.  Alkyl aryl ethers when react with HX yields phenol and alkyl halide not aryl halide and alcohol.

16.  Propanol has higher boiling point than that of the hydrocarbon, butane.

17.  o-nitro phenol is steam volatile while p-nitrophenol is not.18.  o-nitro phenol os more acidic than ortho methoxyphenol

19.  Boiling point of ethanol is higher than that of methoxymethane.

20.  Carboxylic acids are stronger acids than phenols.

21.  Aromatic carboxylic acids do not under go Friedel-Crafts reaction.

22.  Cyclohexanone forms cyanohydrin in good yield but 2,2,6-trimethylcyclohexanone does not.

23.  There are two –NH₂ groups in semicarbazide. However, only one is involved in the formation of semicarbazones.

24.  During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst, the water or the ester should be removed as soon as it is formed.

25.  Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger acid than phenol.

26.  Anline does not undergo Friedel-Crafts reaction.

27.  pK_b of aniline is more than that of methylamine.

28.  Ethylamine is soluble in water whereas aniline is not.

29.  Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.

30.  Although amino group is o- and p- directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.

31.  Diazonium salts of aromatic amines are more stable than those of aliphatic amines.32.  Gabriel phthalimide synthesis is preferred for synthesizing primary amines.

33.  Aromatic primary amines cannot be synthesized by Gabriel phthalimide synthesis.

34.  Amines are les acidic than alcohols of comparable molecular masses.

35.  Primary amines have higher boiling point than tertiary amines.

36.  Aliphatic amines are stronger bases than aromatic amines.

37.  Aromatic  ammines are less basic than aliphatic ammines.

38.  Ammonolysis of alkyl halide does not give corresponding ammines in pure state.

39.  If NO₂ or COOH groups are attached to a carbon of benzene ring electrophilic substitution becomes difficult.

40.  Haloalkane undergo nucleophilic substitution reaction.

41.  Alcohol act as a weak base.

42.  Phenol exhibit acidic behavior.

43.  Ether possess dipole moment even alkyl groups are identical.

44.  Carboxylic acids have high boiling point than alcohols of comparable molecular mass.

45.  Aldehydes are more reactive than ketones towards Nucleophilic reagents.

46.  Boiling points of ether are lower than isomeric alcohols.

47.  Acetic acid is weaker than chloroacetic acids.

48.  Electrophilic substitution reaction in benzoic acids takes place at meta-position

49.  Alkyl ammines are stronger base than Aryl ammines

50.  Like ammonia ammines are good nucleophiles.

51.  Toluene is more readily nitrated than benzene

52.  Unlike alcohols ,phenols cannot be easily protonated.

53.  Why do aldehydre/ketone behave like polar compounds?

54.  Haloarenes are insoluble in water but soluble in benzene

55.  Formaldehyde gives cannizzaro reaction whereas acetaldehyde not

56.  Carboxylic acid do not give the characteristic test of carbonyl group

57.  Carbonyl compound shows nucleophillic addition reaction.