K.C.S.E Physics Q & A - MODEL 2012PP1QN15

K.C.S.E Physics Q & A - MODEL 2012PP1QN15

​(a) Figure 6 shows a graph of volume against temperature for a given mass of gas.

​Use the graph to determine the absolute zero temperature in 0c.
(b) Figure 7 shows a horizontal tube containing air trapped by a mercury thread of length 24 cm. The length of the enclosed air column is 15 cm. The atmospheric pressure is 76 cm Hg.

​(i) State the pressure of the enclosed air. 
(ii)The tube is now held in a vertical position with the open end facing upwards as shown in Figure 8

​Determine:
(i) The pressure of the enclosed air. 
(II) The length (l) of the enclosed air column. 
(c) In an experiment to demonstrate atmospheric pressure, a plastic bottle is partially filled with hot water and the bottle is then tightly corked. After some time the bottle starts to get deformed.
(i) State the purpose of the hot water. 
(ii) State the reason why the bottle gets deformed. 
(iii) Explain your answer in c (ii) 

answers

(ii) (I) When vertical,
pressure of air = pressure due to mercury column-i-atmospheric pressure
= (24+76)cmHg
= lOOcmHg; 

(c) (i) To expel air; 
(ii) Pressure of air outside the bottle is greater than the pressure of air inside; 
 (iii) Cooling causes condensation of vapour;
 Creating a partial vacuum;