Please help! Chemistry sucks.

[rexsun]

First question


The answer, as the mark scheme says, is B. I chose A and got it wrong..Can anybody kindly explain a bit about that please!!!


The Second one


Could anybody explain how to decide the bond angle in this case? D can be ruled out because N has lone pairs, but for the remaining three , I feel hard.

The third, most important one


Answer is A. What@!? HSO3- act as a base in the second reactoin???? I feel just totally baffled...

OK, the last one, thanks guys for being so patient


The answer is A... But I feel D seems to be more correct. Potassium forms covalent bonding in most cases, thus it should show the greatest tendency... Not sure if I have misunderstood the question however.


Guys, I will wait online for your answer. You guys are more helpful than my teacher , to be honest. Thanks much!

 

[sarah99]

In the first question , it can't be A because Al has a melting point of about 932 which is relatively high compared to the value given in the question. On the other hand , sodium has a low melting point so that's why B is the correct answer.

 

[sarah99]

Question 2 :
The nitrogen atom forms a single bond with the methyl group and a double bond with the other carbon. Therefore it undergoes sp^2 hybridization and so the bond angle will be 120 degrees.

Question 3 :
I'll have to think about this one

Question 4 : Neon is definitely wrong since its unreactive. This leaves us with magnesium , potassium and aluminium. The reason A is the answer is because the Al3+ ion is a strong polarizing agent. This is because it's small and highly charged so it causes great distortion of the electron cloud of the anion and therefore the bond is no longer entirely ionic.

 

[sarah99]

For Question 3 , hso3- is a base because its reacting in both reactions with H+ which is acidic.
I hope this was helpful ^^

 

[rexsun]

For Question 3 , hso3- is a base because its reacting in both reactions with H+ which is acidic.
I hope this was helpful ^^

Thanks so much. I have exam tomorrow, your reply is really helpful!!

 

[Asad rehman]

In last question the correct ans is Al because its more towards right than other listed animals and moving from left to right non-metallic character increases and Ne is already noble gas.