Answer:
0.756 J/g°C
Step-by-step explanation:
The specific heat capacity of any material is defined as the quantity of heat (J) absorbed per unit of mass (kg) with an increase in temperature is 1 °C.
Specific heat capacity is defined as:

given, Q = 42J, m(mass) = 3.1g and ΔT = 17.9 °C

S = 0.756 J/g°C