Differentiate among opaque, translucent and transparent materials, giving one example of each.

Pick five objects from the word box given as Fig. 4.1 which are opaque and would sink in water.

chalk, iron, Wood, aluminium, candle, cotton usually look different from each other. Give some properties by which we can prove that materials are different.

Why do you think oxygen dissolved in water is important for the survival of aquatic animals and plants?

Sugar, salt, mustard oil, sand, sawdust, honey, chalk powder, petals of flower, soil, copper sulphate crystals, glucose, wheat flour are some substances given to paheli. She wants to know whether these substances are soluble in water or not. Help her in identifying soluble and insoluble substances in water.