Which of these Amendment Act added language in 8th schedule of our Constitution?

Which of these Amendment Act had not added a schedule in our Constitution?

Tenth schedule was added in constitution by which amendment act?

Which three languages have been added to the Eighth Schedule of the Constitution by 71st Amendment?

Which one of the following languages was added to the Eighth Schedule by a Constitutional Amendment in 1967?

Maithili language was added in eighth schedule by which amendment act?