Question 5. What is the physical state of water at (a) 25°C (b) 0°C (c) 100°C?
Answer: (a) Liquid, (b) Solid and (c) gas.
Question 6. Give two reasons to justify
(a) Water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.
Answer: (a) water at room temperature is liquid because at this temperature (i)it has fixed volume and (ii)it can flow.
(B) An iron almirah is solid at room temperature because at this temperature (i) it has definite shape along with fixed volume and (ii) It can not flow like water and hence does not possess fluidity.
Question 7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Answer: At 273K or 0 ºC the ice will give more cooling than water because it can absorb more heat than water due to its latent heat of fusion.