Dilatação superficial = 2 * Dilatação Linear
DS = 2 DL
beta = 2 alpha
beta = 2 * 12 * 10^-6
beta = 24*10^-6
*******************************
/\S=So*beta*/\t
/\S=250*24*10^-6*50
/\S = 3*10^5*10^-6
/\S = 3*10^-1 m²
*****************************************************************
/\S = 3*10^-1m² = 3*10^-1*10^2dm² = 3*10^1dm² = 30dm²
Letra A
*****************************************************************