It can be either. If the object releasing or absorbing heat remains the same but in a different state the change was physical.Like an ice cube absorbing heat and melting. However, heat being released by a burning candle is chemical, as the wick burns and becomes smoke. A chemical change is results in a product with new properties.
I would say the last one because unlike beta and alpha rays they will have no effect on the mass or atomic number because they are just composed of high energy radiation
Yes, you should memorize them. While it is easy to predict them by looking at a periodic table, you should still have a strong grasp of simpler chemistry such as this before more challenging topics are taught.
