Answer: a. Maintenance
Explanation: E.g. The modern machines require less maintenance.
Answer: c. Occasion
Explanation: E.g. On this happy occasion, I would like to reveal the name of my new company.
Answer: b. Vacuum
Explanation: An empty space without any air/gas is known as vacuum.
E.g. My friend and I vacuumed the whole room.
Answer: b. Satellite
Explanation: Satellite is an artificial body which orbits round the planets in order to gather information/pictures, etc.
E.g. The planet Mercury has no natural satellite.
Answer: b. Fluorescent
Explanation: E.g. Fluorescent lamps are more costly than incandescent lamps.
Answer: b. Achievement
Explanation: E.g. His achievement is worth appreciable.