Given,
Heat energy supplied (Q) = 1300 J
Mass of lead (m) = 0.5 kg
Change in temperature (△t) = (40 – 20)°C = 20° C
Specific heat capacity (c) = ?
From relation,
Q=m×c×△t
Substituting the values in the formula above we get,
1300=0.5×c×20⇒c=0.5×201300⇒c=130 J kg−1K−1
Hence, specific heat capacity of lead = 130 J kg-1 K-1