What do you observe when: 1. water is boiled. 2. a piece of paper is burnt. 3. some … to a bowl containing warm milk and kept for…
- water is boiled
On boiling water changes into steam (gas) physical change.
- a piece of paper is burnt
On burning piece of paper produces carbon dioxide and ash is left behind. Is a chemical change.
- some ice cubes are kept in a glass tumbler
Ice cubes (solid) turn into water (liquid) only state changes (physical change).
- solid ammonium chloride is heated
Solid ammonium chloride on heating changes into vapours (change of state) is physical change.
- an iron nail is kept in tap water for few days
We observe reddish brown coating on the nail called rust (entirely new substance) is chemical change.
- a spoon of sugar is heated in a pan
When a spoon of sugar is heated in a pan, black (charred sugar) (carbon) is seen. Is a chemical change.
- lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
We observe that hydrogen bums at the mouth of test tube with blue flame and pop sound is heard. It is chemical change.
- quick lime is dissolved in water.
The following two observations will be observed
(i) A hissing sound is observed.
(ii) The mixture starts boiling and lime water is obtained.
- little amount of curd is added to a bowl containing warm milk and kept for five hours.
When a little amount curd is added to a bowl containing warm milk and kept for five hours, a permanent change occured.
The milk will change to curd. On boiling water changes into steam (gas) physical change.