Track quiz
Here are the rules this track used. Read them, then try the questions.
| Idea | The rule |
|---|---|
| Fold and cut | Folding and cutting change the shape. The paper stays paper. No new substance is made. |
| Ice, water and steam | Ice, water and steam are one substance in three forms. The weight stays the same. |
| Dissolving | Sugar in water is spread too thin to see. Drying the water brings the sugar back. |
| Cannot be undone | No new substance is made. Some of these changes still cannot be undone. |
| A new substance | A chemical change makes a new substance. Lime water turning milky shows carbon dioxide. |
| Five signs | A sign is only a clue. Ask if the stuff at the end is new. |
| One candle | Wax melting is physical. Wax vapour burning is chemical. A candle has both. |
| Two questions | Ask two questions. Is something new made? Can we undo it? |
| Slow changes | Rocks break in physical changes. Some rocks change into new substances. Most of these changes are slow. |
| Burning | Combustion needs a combustible substance and oxygen from the air. It gives out heat, light or both. |
| Fire triangle | A fire needs three things: fuel, oxygen and enough heat. Take one away and the fire goes out. |
| Word equations | In a word equation, the starting substances are on the left. The new substances are on the right. |
| Useful and harmful | A desirable change helps us. An undesirable change harms us. The same change can be both. |
Ice melts into water. Which kind of change is this?
A sheet of paper burns to ash. Which kind of change is this?
Salt is stirred into water and dissolves. How can you get the salt back?
Vinegar and baking soda fizz. The gas turns lime water milky. What is the gas?
Steam rises off a boiling pan. A gas comes off. Is something new made?
A candle burns and then goes out. What happens to the melted wax pool?
A clay pot breaks. Which pair is right?
Water freezes in a crack and splits a rock. What kind of change is this?
A cover is put over a burning oil lamp. The flame goes out. What is the reason?
A fire blanket is spread over a small fire. Which side of the fire triangle is cut off?
Read: magnesium + oxygen → magnesium oxide. Which side holds the new substance?
Food rots in a cupboard. The same rot in a compost pit is useful. What does this show?
Your NCERT book has the same chapter. Read it with these pictures in mind.
Ask what is there at the end. Ask separately if you can undo it.
The next track is Adolescence: A Stage of Growth and Change. It asks careful questions about people.