Please ans 14th Q:

Q. 14. Will the weight of an ' Iron sinker plus cork' combination in water be more or less than that of the iron sinker along in water ? Give a very brief explanation for your answer. 
 

The weight of an 'iron sinker + cork' combination in water will be less than that the iron
sinker alone in water because cork alone floats with its large portion out of surface of
water, So for its complete immerssion under water an extra upthrust will be exprienced
by the iron sinker.