21. The e.m.f of a storage battery depends upon
a. size of the electrodes
b. shape of the cell
c. nature of electrodes
d. all of the above

22. The internal resistence of a dry cell is of the order of
a. 0.2 to 0.4 ohm
b. 1 to 1.5 ohm
c. 2 to 5 ohms
d. 1 to 15 ohms

23. For a group of cells when internal resistance of the group is equal to the external resistance due to load , the battery will give
a. maximum voltage
b. maximum current
c. maximum energy
d. maximum ampere-hours

24. One ampere hour charge is equivalent to
a. 36 coulombs
b. 360 coulombs
c. 3600 coulombs
d. 36000 coulombs

25. When water is added to sulphuric acid
a. colour of acid changes
b. lot of heat is generated
c. water starts boiling
d. acid particles get separated

26. The electro-chemical reactions are not reversible in case of
a. primary cells only
b. secondary cells
c. both primary and secondary cells

27. The energy in a lead acid battery is stored in the form of
a. electrostatic charge
b. non-flowing current
c. chemical energy
d. nuclear energy

28. The electrolyte in a leclanche cell is
a. dilute hydrochloric acid
b. aqueous solution of ammonium chloride
c. pyrogallic acid
d. lead stearate

29. The electrode for a battery must be
a. a good conductor of electricity
b. a bad conductor of electricity
c. a semi-conductor
d. an insulator

30. For a discharged lead-acid battery the specific gravity of the acid is
a. 0.9
b. 1.0
c. 1.12
d. 1.3