an electron enters a magnetic field vertically downwards with a velocity v from east.the electron is deflected along?

The force acting on them is F= e(v×B). Now, charges of electron and proton have opposite sign. Again from Newtons law, F=ma where a is the acceleration. So, 

   e(v×B)=ma. 

It is v×B. So, along (-x)×(-z).

So, it is -y direction, or here, north.

I’m extremely sorry. I didn’t considered the negative charge of electron. taking a minus in above answer, the answer becomes south.

Is it ok?