Class 12 Chemistry Unit Test Model Paper

UNIT TEST – I (2021-22)

CLASS-XII

CHEMISTRY M:M 20

Q.1 The correct order of the packing efficiency in different types of unit cell is: (1)

a) fcc > bcc < simple cubic

b) fcc > bcc =simple cubic

c) fcc > bcc > simple cubic

d) bcc> fcc < simple cubic

 

Q.2 The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called ___________. (1)

(a) Cell potential

(b) Cell emf

(c) Potential difference

(d) Cell voltage

 

Q.3 An electrochemical cell can behave like an electrolytic cell when ______. (1)

(a) E cell= 0

(b) E cell > Eext

(c) Eext > E cell

(d) E cell = Eext

 

Q. 4 Calculate Molar conductance at infinite dilution for acetic acid .(2)

(given λ m at infinite dilution for HCl=425 ohm-1 cm2 mol-1, λm at infinite dilution for NaCl=188 ohm-1cm2mol-1, λm at infinite dilution for CH3COONa=96 ohm-1cm2mol-1).

 

Q.5 Which point defect in crystals of a solid does not change the density of the solid and why?(2)

 

Q.6 ZnO crystal on heating acquires the formula Zn1+xO. Give reason. (2)

 

Q.7 Give construction and working of fuel cell. (3)

 

Q.8 An element with molar mass 2.7 X 10-2 kg mol-1 forms a cubic unit cell with edge length 405 pm. If its density is 2.7 X 103 kg m-3, find the nature of the cubic unit cell ? (3)

 

Q.9 The reduction potentials of Cu2+/Cu and Ag+/Ag electrodes are 0.34V and 0.80V respectively. For what concentration of Ag+ions will the EMF of the cell at 250C is zero? Given that the concentration of Cu2+ is 0.01M. (5)

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