Changes Around Us: Physical and Chemical
Melting ice can freeze back into ice, but burnt paper never returns, and this chapter of the NCERT Curiosity textbook for Class 7 builds on that contrast. It sorts changes into physical ones, where only state, shape, or size alters, and chemical ones, where entirely new substances form. Activities with rusting iron, curdling milk, cooking food, and mixing baking soda with vinegar reveal signs such as colour change, gas release, and heat, helping learners decide which kind of change they see.
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