What is the noun form of the word beneficial?

এই টপিকের আরও কিছু প্রশ্ন:

• The mother sat vigilantly beside the sick baby. Here vigilantly is?
• The verb form of the noun Origin is?
• The day of my sisters marriage is drawing near. The word near is?
• The adjective of the word authority is?
• She works hard. What part of speech is the word hard?