E=mcθ
where E is the energy added,m is the mass,c is the specfic heat capacity and θ is the change in temprature.
making m subject u get E/cθ=m
θ=(30-20)=10
plugging the values we get :
[tex] \frac{4750}{1900*10} [/tex]
solving it we get the answer that is 0.25kg or 250 grams