Page 71 - CT&AI_CLasa_7_Part_1

What should be filled in place of 'X'? Which observation supports the idea of
(Pattern Recognition) erosion? (Decomposition)
(a) Only shape changes (a) Breaking rocks

(b) Only state changes (b) Movement of sediments

(c) New substance is formed (c) Burning wood

(d) No change occurs (d) Melting ice

6. Which pattern do the following changes 9. A student is given four observations:
follow?
1. A solid turns into liquid on heating and
• Rusting of iron becomes solid again on cooling.
• Burning of wood
2. A substance burns and produces heat,
• Formation of curd (Pattern Recognition) light, and ash.
(a) All these changes are reversible. 3. A white liquid turns milky when a gas is
passed through it.
(b) All these changes are physical
changes. 4. A metal object develops a reddish-brown
coating over time.
(c) All these changes form new
substances. The student is asked to classify these changes
on the basis of characteristics such as
(d) All these changes involve change reversibility, formation of new substances,
in shape only. and energy changes.
7. Identify the correct pattern: Which pair represents only chemical changes?

Set A: Melting butter, boiling water, freezing (Decomposition)
water
(a) 1 and 2 (b) 1 and 4
Set B: Burning paper, rusting iron, baking cake
(Pattern Recognition) (c) 2, 3 and 4 (d) 1, 3 and 4

(a) Both sets include reversible changes. 10. A process occurs as follows:

(b) Set A contains reversible changes, Step 1: Rocks break into smaller pieces.
while set B contains irreversible Step 2: These pieces are transported.
changes. Step 3: They settle in new locations.

(c) Set A includes chemical changes, Which option correctly identifies these three
while set B includes physical steps? (Algorithmic Thinking)
changes.
(a) Combustion weathering erosion
(d) Both sets contain irreversible
changes. (b) Deposition combustion erosion

8. Over many years, rocks break into smaller (c) Erosion deposition weathering
pieces due to heat, water, and plant roots.
These pieces are then carried away by rivers (d) Weathering erosion deposition
and wind and are deposited in other places.

Changes Around Us: Physical and Chemical 69