One Word Substitution

A dictionary is a reference book that lists words in alphabetical order and provides their definitions. A diary is for personal records, and a directory lists names or addresses.

Agenda means a list, a plan or an outline of things to be done or discussed at a meeting.

Intellect usually is in reference to one's intelligence, power of thought or mind.

Impostor is a person who deceives others, especially by assuming a false identity.

 Here, indelible is the correct option. Illegible is something that is not clear enough to be read, incorrigible is something that is incapable of being corrected or amended and irrevocable is something that is not possible to be revoked.

 Here, ethnology is the correct option. Archaeology is the study of ancient societies, history is the study of past events, particularly in human affairs and anthropology is the science of human zoology, evolution, and ecology.

 Here, epilogue is the correct option. Dialogue is a conversation between two or more people as a feature of a book, play, or film. Epitome is a summary of a written work and obituary is a notice of a death, especially in a newspaper, typically introducing a biography of the deceased person.

 Here, necrophobia is the correct option. Lygophobia is the fear of darkness, dentophobia is the fear of dentist and zeusophobia is the fear of God.

 Here, megalomania is the correct option. Dromomania is the mania for travel, kleptomania is the mania for stealing things and logomania is the mania for talking.

 Here, autocracy is the correct option. Democracy is a system of government by the whole population or all the eligible members of a state, typically through elected representatives. Monarchy is a form of government with a monarch at the head and plutocracy is the government by the wealthy.

Explanation for option 1: This is incorrect. Explanation for option 2: This is incorrect. Explanation for option 3: This is the correct. Explanation for option 4: This is incorrect.

Explanation for option 1: A catalogue is the list of books in a library. Explanation for option 2: This is correct. Explanation for option 3: A book of names and telephone numbers is known as a directory. Explanation for option 4: This is not valid as “option 2” is correct.

Explanation for option 1: “Astronomy” stands for a study of stars. Explanation for option 2: This is correct. Explanation for option 3: “Trigonometry” is the science of triangles. Explanation for option 4: A study of coins is called “Numismatics”.

Explanation for option 1: A collection of monkeys is called “troop”. Explanation for option 2: A collection of wild animals is called “zoo”. Explanation for option 3: A group of sheep is called “herd”. Explanation for option 4: A collection of birds or insects is called “flight”.

Option 4 is the correct word here.