HELP: Destroyer questions

[stpele01]

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Hello future dentists,
I was doing gen chem Destroyer questions and there are some questions I have no idea how they got to the answer. Please, help:

question 108: which reactions shown below will not yield a precipitate:
a- AgNO3 + KBr
b- Pb(NO3)2 + KCl
c- NaNO3 + NH4Cl
d- BaBr2 + Na2SO4
e- CaI2 + (NH4)2CO3
Answer is c

question 117: For silicon, which ionization energy would you predict to be exceptionally large as compared to the preceding ionization energy value?
a- 1st
b- 2nd
c- 3rd
d- 4th
e- 5th
answer is E

I got both answers right by process of elimination + luck but I need to know how to actually solve them😕

thanks again for all the help.

 

[joeeeey3]

108:

NaNO3 + NH4Cl -> NaCl + NH4NO3

according to solubility rule, salt with group 1 metal and NH4, NO3, ClO4, C2H3O2 are always soluble.
thus this will not precipitate to form solid

117. silicon has 4 valence electrons. since the valence electrons are loosely held, they can easily be taken out. However, the 5th electron is one shell closer to the nucleus and thus more tightly held. therefore it will require significantly more amount of energy to take it out