Answer:
10500 J/kg/*C
Explanation:
Quantity of heat required=mass of substance x specific heat capacity x change in temperature
Quantity of heat required=0.25 x 4200 x [30-20]
Quantity of heat required=0.25 x 4200 x 10
Quantity of heat required=10500 J/kg/*C
3.51 × 10^-7m
Explanation:
Refractive index = wavelength of the light in air ÷ wavelength in the medium
wavelength in the medium = wavelength of the light in air ÷ refractive index
= 5.4 * 10^-7 ÷ 1.54
= 3.51 × 10^-7m