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(a). Why do acids not show acidic behaviour in the absence of water? (b). Why does an aqueous solution of an acid conduct electricity? (c). Why does distilled water not conduct electricity whereas rain water does?

Give reasons for the following : (i) Distilled water does not conduct electricity but rain water does. (ii) Acids do not show acidic behaviour in the absence of water. (iii) A solution with pH less than 7 is acidic. (iv) HCI shows acidic behaviour in aqeous solution but C_(2)H_(5)OH does not .

Answer the following: (a) The top of the atmosphere is at about 400 kV with respect to the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth, the field is about 100 Vm^(-1) . Why then do we not get an electric shock as we step out of our house into the open? (Assume the house to be a steel cage so there is no field inside!) (b) A man fixes outside his house one evening a two metre high insulating slab carrying on its top a large aluminium sheet of area 1m^(2) . Will he get an electric shock if he touches the metal sheet next morning? (c) The discharging current in the atmosphere due to the small conductivity of air is known to be 1800 A on an average over the globe. Why then does the atmosphere not discharge itself completely in due course and become electrically neutral? In other words, what keeps the atmosphere charged? (d) What are the forms of energy into which the electrical energy of the atmosphere is dissipated during a lightning? (Hint: The earth has an electric field of about 100 Vm^(-1) at its surface in the downward direction, corresponding to a surface charge density = 10^(-9)C m^(-2) . Due to the slight conductivity of the atmosphere up to about 50 km (beyond which it is good conductor), about + 1800 C is pumped every second into the earth as a whole. The earth, however, does not get discharged since thunderstorms and lightning occurring continually all over the globe pump an equal amount of negative charge on the earth.)

a. The top of the atmosphere is at about 400 kV with respectto the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth, the field is about 100 Vm^(-1). Why then do we not get a electric shock as we step out of our house into the openy (Assume the house to be a steel cage so there is no field inside!) b. A man fixes outside his house one evening a two metre high insulating slab carrying on its top a large aluminium sheet of area 1m^(2) . Will he get an electric shock if he touches the metal sheet next morning? c. The discharging current in the atmosphere due to the small conductivity of air is known to be 1800A on an average over the globe. Why then does the atmosphere not discharge itself completely in due course and become electrically neutral? In other words, what keeps the atmosphere charged? d. What are the forms of energy into which the electrical energy of the atmosphere is dissipated during a lightning? (Hint: The earth has an electric field of about 100 Vm^(-1) at its surface in the downward direction, corresponding to a surface charge density =-10^(-9) Cm^(-2) ?.

(a). Explain why, ionic comppounds conduct electricity in solution whereas covalent compounds do not conduct electricity. (b). Which of the following will conduct electricity and which not? MgCl_(2),C Cl_(4),NaCl,CS_(2),Na_(2)S Give reason for your choice.

(a) A longitudinal wave propagating in a water-filled pipe has intensity 3.00xx10^(-6) W//m ^(2) and frequency 3400 H_(Z) . Find the amplitude A and wavelength lambda of the wave . Water has density 1000 kg//m ^(3) and bulk modulus 2.18xx10^(9) Pa . (b) If the pipe is filled with air at pressure 1.00 xx10^(5) Pa and density 1.20 kg//m^(3) , What will be the amplitude A and wavelength lambda of a longitudinal wave the same intensity and frequency as in part (a) ? (c ) In which fluid is the amplitude larger, water or air? What is the ratio of the two amplitude ? Why is this ratio so different from/ Conider air as diatomic.