Let the speed of the boat in still water and the speed of the current be ‘x’ km/hr and ‘y’ km/hr, respectively Upstream speed of the boat = (x – y) = 240/12 = 20 km/hr Or, 30 – y = 20 Or, y = 30 – 20 = 10 km/hr Therefore, downstream speed of the boat = 30 + 10 = 40 km/hr Required time taken = 140/40 = 3.5 hours
Bronze is an alloy of-
The pH of a neutral solution is —
The fuel that is used in modern submarines is -
The noble gas used in radiotherapy is
The element used in the manufacture of safety matches is —
Manganite is an ore/mineral of
Petroleum is a mixture of-
The nucleus of an atom consists of-
The gas used for filling weather balloons is-
The chemical name of'Common salt’