MCQ Help Watch

TheTennisOne
Badges: 2
Rep:
?
#1
Report Thread starter 1 year ago
#1

Can someone explain Part B and C please, I mean I guessed correctly but I dont really understand why in this case, just because I know halogens make HX but does group 2 make MH2?
0
reply
Kozmo
Badges: 8
Rep:
?
#2
Report 1 year ago
#2
The key thing about this question is that it states the elements have consecutive atomic numbers.

Assuming the period doesn't change, which it could, but based upon the questions asked seems unlikely:

As one of them is an inert gas (that being B due to it having the greatest first ionisation energy) then the others must be a part of group 7 (that being A - next highest ionisation energy), group 6 (D for the same reason as previous) and group 5 (for the same reason as the other two).

Thus, X is evidently the halogen, so is A.

Y is a compound that bonds to two hydrogen atoms - group 6 elements are elements which regularly do this e.g H2O. Thus, Y must be D.
0
reply
TheTennisOne
Badges: 2
Rep:
?
#3
Report Thread starter 1 year ago
#3
(Original post by Kozmo)
The key thing about this question is that it states the elements have consecutive atomic numbers.

Assuming the period doesn't change, which it could, but based upon the questions asked seems unlikely:

As one of them is an inert gas (that being B due to it having the greatest first ionisation energy) then the others must be a part of group 7 (that being A - next highest ionisation energy), group 6 (D for the same reason as previous) and group 5 (for the same reason as the other two).

Thus, X is evidently the halogen, so is A.

Y is a compound that bonds to two hydrogen atoms - group 6 elements are elements which regularly do this e.g H2O. Thus, Y must be D.
h2o is not ionic though so surely it cannot be group 6
0
reply
Kozmo
Badges: 8
Rep:
?
#4
Report 1 year ago
#4
(Original post by TheTennisOne)
h2o is not ionic though so surely it cannot be group 6
Ahh, yes, good point - my bad, didn't entirely read the question.

So, presumably Y is a group 2 compound and so the consecutive elements continue over a period. But, that still works nonetheless - Y must be D for the following reason(s):

Let's assume that we're initially talking about period 3:

A = the halogen, group 7 period 3 = atomic number 17 (chlorine). = compound X
B = the noble gas = atomic number 18 = higher ionisation energy than the halogen as it is further right.
C = a group 1 compound. = ionisation energy drops as we are moving up to the next full energy level.
D = a group 2 compound (in our theoretical example atomic number 20) = ionisation increases as the proton number increases while shielding / distance from nucleus stays constant, but still lower than A and B because it's in a higher energy level (4s in our case, instead of 3p). = compound Y

It therefore appears that the order they gave the answers in (A, B, C, D) was the literal order in which the atomic number increased. If that had of been more clear, the question would have been much easier in my eyes.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Roehampton
    Department of Life Sciences; Department of Psychology Undergraduate
    Thu, 21 Feb '19
  • Edge Hill University
    Undergraduate and Postgraduate - Campus Tour Undergraduate
    Thu, 21 Feb '19
  • St George's, University of London
    Postgraduate Open Evening Postgraduate
    Thu, 21 Feb '19

Is the plastic tax enough to protect the environment?

Yes (4)
4%
No (96)
96%

Watched Threads

View All