The closest date for which I can find listings is 1922, and there are several possible denominations. Please check your bill again and post a new question with its exact date and its denomination.
Please check your bill again and post a new, separate question. There are no 1920-series US $20 bills.
Not every old bill is automatically a certificate so it's important to check carefully. If it has a gold seal and says "Gold Certificate", see the question "What is the value of a 1928 US 10 dollar gold certificate?" for values. If it has a green seal and says "Federal Reserve Note", it's not a certificate, it's a Federal Reserve Note. See the question "What is the value of a 1928 US 10 dollar Federal Reserve Note?" for values.
Very definitely. 1922 gold certificates were printed in denominations of $10, $20, $50, $100, $500, and $1000. For more information please see "What is the value of a 1922 US 20 dollar gold certificate?"
Please check again and post a new, separate question. No US $2 bills of any kind were dated 1920 and the last $2 silver certificates were dated 1899.
What is the value of a us blue ink 2 dollar certificate
Please check your bill again and post a new, separate question. There are no 1920-series US $20 bills.
Your bill is most likely a 1905 $20 gold certificate. If correct, please see the question "What is the value of a 1905 US $20 gold certificate?" for more information.
Please check your bill again. As the banner across the top indicates, it's a silver certificate, not gold. All gold certificates were withdrawn in 1933. There's more information at the question "What is the value of a 1957 US 1 dollar silver certificate?"
Not every old bill is automatically a certificate so it's important to check carefully. If it has a gold seal and says "Gold Certificate", see the question "What is the value of a 1928 US 10 dollar gold certificate?" for values. If it has a green seal and says "Federal Reserve Note", it's not a certificate, it's a Federal Reserve Note. See the question "What is the value of a 1928 US 10 dollar Federal Reserve Note?" for values.
These coins were not made in 1920. Ask another question with the correct date.
Yes. The 1928 series was the last for circulating gold certificates, and $10 was the lowest denomination. There's more information at the question "What is the value of a 1928 US 10 dollar gold certificate?"
Please check again and post a new, separate question. The US stopped issuing gold coins and gold certificates in 1933.
The US Treaury only printed $10 Gold Certificates bearing the Series Date of 1928 and 1928A.
Please check the banner across the top of your bill. It should say United States Note, not gold certificate. There's never been a $2 Gold Certificate and in any case, all gold certificates of any denominations were withdrawn from circulation in 1933. There's more information the at question "What is the value of a 1963 US 2 dollar bill?".
Very definitely. 1922 gold certificates were printed in denominations of $10, $20, $50, $100, $500, and $1000. For more information please see "What is the value of a 1922 US 20 dollar gold certificate?"
Any red-seal US $2 bill dated 1928 or later is a United States Note and not a certificate. Certificates were exchangeable for silver or gold, and carried the words Silver Certificate or Gold Certificate across the top. Please see the question "What is the value of a (date) US 2 dollar bill?" for more information, where (date) is your bill's series date.
Please check again and post a new question. The U.S. stopped issuing gold coins and gold certificates in 1933.