A driver having a definite reaction time is capable of stopping his car over a distance of 30 m on seeing a red traffic signal, when the speed of the car is 72 km/hr andover a distance of 10 m when the speed is 36 km/hr. Find the distance over which he can stop the car if it were running at a speed of 54 km/hr. Assume that his reaction time and the deceleration of the car remains same in all the three cases.

Answer

There are some method by which we can soften the water sample .
`{:("(a)","By boiling :",2HCO_(3)^(-)rarrH_(2)O+CO_(2)CO_(3)^(2-),),("or","By Slaked lime :",Ca(HCO_(3))_(2)+Ca(OH)_(2)rarrCaCO_(3)+2H_(2)O,),(,,Ca^(2+)CO_(3)^(2-)rarrCaCO_(3),),("(b)","By Washing Soda :",CaCl_(2)+Na_(2)CO_(3)rarrCaCO_(3)+2NaCl,),("(c)"," ionexchange resins",Na_(2)R+Ca^(2+)rarrCaR+2Na^(+),),("(d)","By adding chelating agents like",(PO_(3)^(-))_(3)"etc.",):}`