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NCERT Solutions Curiosity Chapter 7 .4.1 Seepage of water beneath the Earth — Activity 7.5: Let us investigate

Book page 997 Updated on2026-09-05

Q1.
Predict the amount of water flowing out of each bottle.
Answer

200 mL of water is poured into each inverted bottle — one holding clay, one sand and one gravel — and the water is collected for 10 minutes (Fig. 7.10). A sensible prediction is:

Bottle 3 (gravel) → most water collected, and fastest
Bottle 2 (sand) → a moderate amount
Bottle 1 (clay) → least water collected, and slowest
Reason for the prediction: the bigger the spaces between the particles, the more easily water can pass through. Gravel particles are large, with wide gaps between them; sand particles are much smaller; clay particles are the finest of all and pack together very tightly, leaving almost no open path for water.
Check it yourself: use the same bottle size, the same 200 mL of water and the same 10 minutes for all three, otherwise the comparison is not fair.
Q2.
Compare the amount of water that comes through each bottle.
Answer

On performing the activity, the water comes through in this order: gravel > sand > clay. Here is Table 7.5, completed.

Bottles filled withPredictionObservation
Seepage of water (very slow/slow/fast)Seepage of water (very slow/slow/fast)
Bottle 1 (Clay)Very slowVery slow — only a little water trickles into the beaker; most of it stays above the clay
Bottle 2 (Sand)SlowSlow — a fair amount of water collects, but it takes time
Bottle 3 (Gravel)FastFast — almost all the water runs through quickly and fills the beaker
Why it happens: the spaces between gravel particles are wider than those in sand and clay, so water can seep through gravel more easily. In clay the particles are extremely fine and closely packed, so the water is held back.
Did you know? This is why a pond dug in clayey soil holds water for months, while the same pond dug in sandy soil empties within days.
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