26 Sulphur and selenium (Se) are in the same group of the Periodic Table.
From this, we would expect selenium to form compounds having the formulae
A SeO, Na2Se and NaSeO4.
B SeO2, Na2Se and NaSeO4.
C SeO2, Na2Se and Na2SeO4.
D SeO3, NaSe and NaSeO4.

Question

26 Sulphur and selenium (Se) are in the same group of the Periodic Table.
From this, we would expect selenium to form compounds having the formulae
A SeO, Na2Se and NaSeO4.
B SeO2, Na2Se and NaSeO4.
C SeO2, Na2Se and Na2SeO4.
D SeO3, NaSe and NaSeO4.

anonymous · Answer

@Callisto @apoorvk @wasiqss

apoorvk · Answer

Okay, okay - so, that means Selenium has two electrons missing from its octet as well and like sulfur it has d-orbitals as well - right?

So let's first think about its compound with Na.

What's the oxide of Na? The primary oxide form?

callisto · Answer

S = SO2 = ...?
Na2O  => Na2S => ...?
Na2SO4 => ... ?
Probably, replace S  by Se is okay :|
Not sure though

anonymous · Answer

Na2S....? @apoorvk

anonymous · Answer

and hw do u we find the next one....

anonymous · Answer

any methods

callisto · Answer

O, S and Se are in the same group.
Na2O  =>   Na2S  => the next one is...?

anonymous · Answer

hw? i need a method for that

callisto · Answer

Na => +
O => 2-
Balance the charge => Na2O

anonymous · Answer

yeah then=0, and if we take from Se04
Se=+8 where as 04=-8
so its c

callisto · Answer

Is Se +8? I don't know :|
Sorry have to go now. Good luck!

anonymous · Answer

no i mean balancing the charges i get using calculate the oxidation state number...

anonymous · Answer

okay bye and thanks @Callisto

callisto · Answer

It's not about oxidation number... it's about the charge!

callisto · Answer

I think...

anonymous · Answer

hm....@apoorvk  is it?

apoorvk · Answer

It actually is about both oxidation states and charge. Oxidation states are pretty important, and take care multiple oxidation states can exist for elements with further vacant d-orbitals.

Comparing with sulfur would be a good idea.

anonymous · Answer

multiple is only when we consider about transition, so it wont matter in this case:)

anonymous · Answer

i jst wanted to check if my method is correct @apoorvk

anonymous · Answer

12 In one molecule of carbon dioxide, CO2, what is the total number of electrons present and how
many are involved in bonding between the carbon and oxygen atoms?
total number of electrons electrons involved in bonding
A 16            4
B 16            8
C 22            4
D 22            8

anonymous · Answer

@apoorvk @Kryten

anonymous · Answer

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does this help