Which of the following are physical properties? Radioactivity
Color
Temperature
Flammability
Texture
Reactivity

Explanation:

The properties that are observed or measured without changing the composition of matter are called physical properties.

color, Temperature, Texture are the physical properties as the composition of matter remains the same.

On the other hand, Radioactivity, Flammability and Reactivity comes under chemical property as during the chemical reactions there might be some changes in the properties.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.