Answer:
The atomic numbers of four elements A, B, C, and D are 6,8,10, and 12 respectively. The two elements which can react to form ionic bonds (or ionic compounds) are B (8= 2,6) and D (12 =2,8,2). So D donates its two electrons to B to fulfill their octet.
Explanation:
Answer:
20 molecules of oxygen gas remains after the reaction.
Explanation:

Molecules of ethyne = 52
Molecules of oxygen gas = 150
According to reaction, 2 molecules of ethyne reacts with 5 molecules of oxygen gas.
Then 52 molecules of ethyne will react with:
of oxygen gas.
As we can see that we have 150 molecules of oxygen gas, but 52 molecules of ethyne will react with 130 molecules of oxygen gas. So, this means that ethyne is a limiting reagent and oxygen gas is an excessive reagent.
Remaining molecules of recessive reagent = 150 - 130 = 20
20 molecules of oxygen gas remains after the reaction.
Answer:
can you be more clear with your question :
No, they can have potential energy
The reasonable ground-state electron configuration is: 1s2 2s2 2p6 3s2 3p6 4s2 4d8