Add a nail in cuso4 sodium, the colour of cuso4 disappears why?

Aparticle with mass 1.81×10−3 kg and a charge of 1.22×10−8 c has, at a given instant, a velocity v⃗ =(3.00×104m/s)j^. what are the magnitude and direction of the particle’s acceleration produced by a uniform magnetic field b⃗ =(1.63t)i^+(0.980t)j^?

Can anybody me with this? ? (picture included.)

Ineed the answer to question 1 , i’m desperate