11. Ampere-hour efficiency of the battery is
a. 60%
b. 70%
c. 80%
d. 90%

12. Watt hour efficiency of the battery is
a. 85%
b. 75%
c. 70%
d. 66%

13. The indication of the state of charge of a battery is best given by
a. specific gravity of electrolyte
b. temperature of electrolyte
c. colour of electrolyte
d. level of electrolyte

14. Common impurity in battery electrolyte is
a. sodium chloride
b. iron
c. lead sulphate
d. dust

15. Open circuit voltage of a fully charged lead acid cell is
a. 1.9 V
b. 2.0 V
c. 2.7 V
d. 2.5 V

16. The capacity of storage battery is expressed as
a. the number of recharges it can take
b. time for which it can be used
c. the number of cells it contains
d. ampere hour it can deliver

17. On watt hour basis the efficiency of a lead acid battery is in the range
a. 90 to 95 %
b. 80 to 85%
c. 70 to 85%
d. 60 to 70%

18. Trickle charge is required for
a. lead acid batteries
b. nickel iron cells
c. primary cells
d. all of the above

19. A wet battery cover in case of lead acid battery indicates
a. excessive gasing during charging
b. leaky seals at covers
c. overfilling of the battery
d. any of the above

20. Internal resistance of a battery is due to
a. resistance of electrolyte
b. resistance of electrodes
c. surface contact resistance
d. all of the above