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COMPOUNDS OF TELLURIUM.
774. How is telluretted hydrogen obtained, and what is the weight of a litre of it at N.T.P.?
775. Write the formulæ of all the corresponding compounds of sulphur, selenium, and tellurium which contain (a) hydrogen, (6) chlorine, (c) oxygen, and (d) hydrogen and oxygen.
776. How much oxygen at N.T.P. would be taken up in each case by burning 69 grammes of (a) sulphur, (6) selenium, (d) tellurium, in air?
SECTION II.-METALS AND THEIR
777. How are the metals distinguished from the nonmetals ? Name some elements which cannot well be placed in either class.
778. To what substances was the name metalloid originally applied, and how is it now used ?
779. How would a chemist proceed to examine a new element so as to decide whether to class it with the metals or the non-metals ?
780. What is meant by each of the following terms applied to metals ? (a) tenacity, (6) malleability, (c) ductility, (d) lustre, (e) conductivity for heat and electricity.
781. How does increase of temperature usually affect (a) the malleability, (6) the tenacity, (c) the conductivity of metals ?