The capacity in litres of a tank 0.5 m long, 12 cm wide and 60 mm deep is :

Length =0.5m; width =12cm×1m100cm=0.12m Depth =60mm×1m1000mm=0.06m.∴  Capacity = Length × width × depth  =0.5m×0.12m×0.06m =3.6×10−3m3=4×10−3m3=4L                                                                   ∴1L=10−3m3In case of multiplication, the result is given in minimum number of significant figures(see chapter, 2) (i.e., 1 as in 0.5). So, 3.6 is taken as 4. So, the correct answer is (a).