Question Whether ~ or not, etc

Dear native English speakers,
Would you check my sentences?
Do they sound right? Do any of them sound unnatural?

1a) I don't know whether Tom will come to the party or not.
1b) I don't know if Tom will come to the party or not.
1c) I don't know whether Tom will come to the party.
1d) I don't know if Tom will come to the party.

2a) Do you know whether Daniel is from England?
2b) Do you know if Daniel is from England?

3a) You can't tell whether he is American or not by his look.
3b) You can't tell if he is American or not by his look.
3c) You can't tell whether he is American by his look.
3d) You can't tell if he is American by his look.

4a) Daniel asked us whether we like Canada or not.
4b) Daniel asked us whether we liked Canada or not.

5a) You can't tell if she is from England or not by her look.
5b) You can't tell if she is from England by her look.

6) Do you know if he will come to Japan next month?

7a) Finally I got my own house.
7b) At last I got my own house.

8) You should bring your own lunch tomorrow.
9) They don't have their own country.

Hirashin

Saying "whether" without listing an alternative sounds odd to me.

I don't know whether he will go to the party or not.
I don't know whether he will drink beer or wine.

Oh, really? Thanks, mdchachi.

Yes, I agree. I think think the natural alternative to "if" is simply the negative, or opposite, which is why it's used in conditional sentences and why you don't need to state it, e.g "Do you know if he's coming tomorrow?" directly implies the opposite, "or not coming tomorrow" but using "whether" simply introduces 2 choices, which could be anything e.g "Do you know whether he's coming tomorrow or......... she's coming tomorrow/he's coming on Friday/he's not coming at all?" The alternative is completely open.

Thanks, Michael2.

Since you said "sound right"

I will add that if this is spoken ENglish

1c) I don't know whether Tom will come to the party… (using inflection to imply the omission of or not) it would be perfectly acceptable to my ear.