How we can define Scalar & vector Quantity?

What is the difference between Vector quantity & Scalar quantity?

How we decide that this physical quantity is Vector or Scalar?

Plz.... Give the answer.

Thanks

Scalar qua. are those which have only magnitude while Vector quantities have direxn also. So you can decide if a quantity is vector or scalar by cheking if it has direction or not,

Ex. 

Vector: Force,Velocity,Displacement

Scalar: Distance, Work,Speed,Time

The answer to your question goes like this. Scalar quantity are those quantities which do not require direction to express themself.They are defined alone by a magnitude.A SIMPLE EXAMPLE SuPPOSE someone asks you your weight. You answer 50kg...thus this is only magnitude and so it is a scalar...And for defiinig your weight you need not tell the direction like 50kg in north direction..These are meaningless. A vector quantity has got magnitude+direction and it also follows vector laws of Algebra. example.If someone asks you a location..you wont just say the name of the place as it will be of no help..you will specify some directions..And specifying directions is a property of vector quanties.Remember vector =scalar +direction. Eg. Velocity=speed+direction. Note; time and electric current are scalars.