Advance Concepts Chemistry

Q: Which of the following orbital box diagrams represents silicon,which has 14 electrons?

(a) :  1s↑↓ 2s↑↓ 2px↑↓ 2py↑↓ 2pz↑↓ 3s2 3px↑↓ 3py 3pz
(b) :  1s↑↓ 2s↑↓ 2px↑↓ 2py↑↓ 2pz↑↓ 3s↑ 3pz↑ 3py↑ 3pz↑ 4s
(c) :  1s↑↓ 2s↑↓ 2px↑↓ 2py↑↓ 2pz↑↓ 3s↑↓ 3px↑ 3py↑ 3pz 4s
(d) :  1s↑↓ 2s↑↓ 2px↑↓ 2py↑↓ 2pz↑↓ 3s↑↓ 4s↑↓ 3px 3py 3pz
(e) :  None of the Above
Answer:  1s↑↓ 2s↑↓ 2px↑↓ 2py↑↓ 2pz↑↓ 3s↑↓ 3px↑ 3py↑ 3pz 4s

Q: A liquid boils at a temperature of 100⁰C, which property of the liquid proves that it is pure water?

(a) :  It does not leave a residue when boiled.
(b) :  It freezes at 0⁰C.
(c) :  Its pH is nearly neutral.
(d) :  It turns white anhydrous copper(II) sulphate blue.
(e) :  None of the Above
Answer:  Its pH is nearly neutral.
Explanation:  A pure substance has a fixed melting and boiling point at the same atmospheric pressure.

Q: The electronic configuration of gallium,atomic number 31 is:

(a) :  [Ar]3s2 3d10 3p3
(b) :  [Ar]4s2 3d10 4p3
(c) :  [Ar]4s2 3d10 4p1
(d) :  [kr]4s2 3d10 4p1
(e) :  None of the Above
Answer:  [kr]4s2 3d10 4p1
Explanation:  Gallium lies between argon(Z=18) and krypton (Z=36).So we can abbreviate the configuration of the first 18 electrons with [Ar].Gallium is in the fourth period since it follows argon ,so the first subshell to fill will be 4s2.The subshell is then filled and we are left with one electron to go in the 4p subshell.The complete configuration is thus [Ar]4s2 3d10 4p1.

Q: Fluorine atoms tend to ______. When they form chemical compounds with metals:

(a) :  lose electrons
(b) :  gain electrons
(c) :  neither lose nor gain electrons… they usually share electrons equally with metals.
(d) :  Fluorine atoms do not form compounds with other atoms…fluorine is an inert gas
(e) :  None of the Above
Answer:  gain electrons
Explanation:  If a fluorine atom gains one electron it will become isoelectronic with the inert gas,neon,and have a stable electron configuration.

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