Question

Halley's comet revolves around the sun once in every 76 Years. This is a:

• A. photochemical change
• B. periodic change
• C. chemical change
• D. irreversible change

Answer 1

Answer: (B)

periodic change

It is a periodic change $-$ because changes that occur after a fix interval of time is known as periodic change.

Here periodic change in $76$ years

Halley's Comet is arguably the most famous comet. It is a "periodic" comet and returns to Earth's vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime. The last time it was here was in 1986, and it is projected to return in 2061.