A black body is at a temperature 300 K. It emits energy at a rate, which is proportional to

Proportional refers to the relationship between two quantities where one changes in direct or inverse relation to the other. If two variables are proportional, their ratio remains constant. For example, in direct proportionality, when one quantity increases the other increases at a constant rate and vice versa for inverse proportionality.

Class 11 Physics Chapter 10 Thermal Properties of Matter covers topics like temperature heat and specific heat capacity. It explains thermal expansion calorimetry and heat transfer methods such as conduction and convection. The chapter also introduces the laws of thermodynamics and the behavior of gases under different conditions and temperature changes.