158 JUNIOR GRADE SCIENCE 



QUESTIONS ON CHAPTER XXV. 



121. Describe carefully, illustrating your answer with a sketch, how you 

 would prepare hydrogen. What precautions would you consider necessary 

 to obtain a jar of it in a pure state ? 



122. How would you obtain hydrogen (a) from water, (6) from dilute 

 acid ? How can it be shown that, when this gas burns, water is formed ? 

 State clearly the properties that distinguish water from other liquids. 



123. Sketch an apparatus by means of which you could burn a jet of 

 dry hydrogen. State how .you would proceed to collect the product of 

 combustion with as little loss as possible and what experiments you would 

 make to test the purity of this product. 



124. Make a careful sketch of the apparatus you would use to show 

 that when hydrogen burns in air a liquid is formed. How is this liquid 

 identified ? 



125. On placing a flask containing cold water over a gas or spirit flame 

 a dew-like deposit is formed ; how would you proceed to collect sufficient 

 of the liquid for the purposes of examination, and what experiments would 

 you perform in order to identify this liquid ? 



126. What is the effect of passing dry hydrogen over heated oxide of 

 copper ? Sketch the apparatus you would employ if asked to make the 

 experiment. 



If water contains 88'89 per cent, of oxygen, what weight and volume of 

 hydrogen would be required to produce a litre of water ? 



