Question 11 MarkTwo harmful changes.AnswerSpoiling of milk.Air pollution.View full question & answer→
Question 21 MarkTwo useful changes.AnswerRipening of mangoCurdling of milk.View full question & answer→
Question 41 MarkTwo natural changes.AnswerLighting in the sky.Earthquake.View full question & answer→
Question 51 MarkTwo irreversible changes.AnswerRipening of a mango.Burning of woodView full question & answer→
Question 61 MarkTwo reversible changes.AnswerMelting of wax.Freezing water into ice.View full question & answer→
Question 71 MarkTwo non-periodic changes.AnswerA meteor moving across the sky.A bird sitting on a tree flies away.View full question & answer→
Question 81 MarkTwo periodic changes.AnswerOccurrence of day and nightchange of seasonsView full question & answer→
Question 91 MarkTwo chemical changes.AnswerBurning of wax candleBurning of wood or paper.View full question & answer→