23) Estimate the time to drill a hole of 20 mm dia, 80 cm depth in mild steel. Take cutting speed of 15 meter /minute and feed of 0.25 mm/revolution.

24) In lead-acid battery, electrode lead peroxide and lead immersed in electrolyte of diluted solution of sulphur acid having _____ percentage of concentration for full charge.

25) Latent heat of ice is

26) A resistance having rating of 10 Ohm 10 W is likely to be a

27) When a resistance of 4 Ohm is placed across the battery terminals, the current flowing is 2 amperes and when the resistance across the battery terminals is increased to 8 Ohm, the current falls to 1 ampere. The internal resistance of the battery is