Answer:
Both are unreactive.
Explanation:
Atom Number of Electrons
A 2
D 10
The two atoms A and D are very stable and unreactive.
Valence electrons the outermost shell electrons in a neutral atom.
The number of valence electrons in A is 2
The number of valence electrons in D is 8
The atoms are stable and unreactive because for A, its two electrons are in the k-shell in which the maximum number of electrons here is 2. It has a noble configuration which makes it stable.
For atom D, the outermost electrons are in the L-shell in which the maximum number of electrons is 8. This also makes it stable and unreactive.
Both atoms will be reluctant to lose or gain electrons.
I think the correct answer is D
Answer:
endothermic reaction
Explanation:
It simply means that you are witnessing<u> an endothermic reaction</u>.
An endothermic reaction is one that absorbs heat energy from its surrounding, thereby leaving the reaction vessel with a lower temperature as compared to before the reaction.
It is as opposed to exothermic reactions which are reactions that give off energy in the form of heat to the surrounding, thereby leaving a reaction vessel warmer than before the reaction.
<em>In this case, the formation of ice crystals outside the test tube means that heat energy has been absorbed by the reaction which leaves the vessel a temperature cold enough to activate the formation of ice. </em>
