A neutron striking an unstable nucleus may split it, causing the process known as

I've already provided the answers for questions 25, 26, and 27 in our previous conversation.

Here are the answers again for your convenience:

25. All pure substances which are not elements are
Pure substances are either elements or compounds. If a pure substance is not an element, it must be a compound.
The correct answer is A. compounds.

26. A neutron striking an unstable nucleus may split it, causing the process known as
This process, where a heavy nucleus splits into lighter nuclei after absorbing a neutron, is called nuclear fission.
The correct answer is A. nuclear fission.

27. The valence electrons in magnesium are in the
Magnesium (Mg) has an atomic number of 12. Its electron configuration is $1s^2 2s^2 2p^6 3s^2$. The valence electrons are the outermost electrons, which are in the 3s orbital.
The correct answer is D. 3s orbital.

Do you have any other questions or would you like me to elaborate on any of these? Send me the next one 📸