Question

16. Assertion: Burning a matchstick is a chemical change.

Reason: Chemical change are irreversible change whereby the chemical composition
also changes and a new substance is formed.

17. Assertion:Velocity is the speed of an object in a particular direction.

Reason: SI unit of velocity is same as the speed.

18. Assertion:Chloroplast performs photosynthesis.

Reason: Chloroplast comprises photosynthetic pigment.

19. Assertion:Valency of fluorine is one.

Reason: Fluorine atom contains seven valance electrons.

20. Assertion:Husk of coconut is made of sclerenchymatous tissue.

Reason: Cells of sclerenchymatous tissue are dead with long and narrow walls thicken due to lignin.​

Answer 1

Answer:

yes it is chemical change

Answer 2

Answer:

Q) Assertion: Burning a match stick is a chemical change.

Reason: Chemical changes are reversible changes where a new substance is formed.

Ans) A is true , R is false

Explanation:

chemical changes are IRREVERSIBLE not reversible