Question

6. Suppose that a particular chemical substance A is "pure" (contains no "impurities"), and that it can be chemically decomposed into two other pure materials B and C. What conclusion can be draw from this? (a) B and C must be elements. (b) A must be an element. (c) B and C must be chemical compounds (d) A must be a chemical compound (e) nonsense -- it is impossible to decompose a pure substance into two other materials 7. A positive ion is an atom that is missing at least one (a) electron. (b) proton. (c) neutrorn (d) proton and one electron (e) none of the above 8. One piece of evidence that Democritus found for his idea that everything is made of atoms was (a) Brownian motion (b) the smell of bread and of other substances (c) the fact that chemicals combine in definite proportions (d) the twinkling of stars, due to our atmosphere. (e) the random, chaotic motions often found in liquids 9. Our Milky Way galaxy contains perhaps 400 billion stars. Suppose that 0.05% (ie. 0.0005) of these stars have planetary systems containing at least one Earthlike planet (one that could conceivably support Earthlike life). Multiply these numbers together to find how many Earthlike planets there are in our galaxy. Express this number in words (thousands or millions, etc.) (a) 200 thousand Earthlike planets (b) 2 million Earthlike planets (c) 200 million Earthlike planets (d) 20 billion Earthlike planets (e) 200 billion Earthlike planets 10. One sheet of paper is about 0.1 mm thick. An atom is about 10-10 m across. About how many atoms thick is one sheet of paper? (a) 1 hundred atoms (b) 1 thousand atoms (c) 1 million atoms (d) 1 billion atoms (e) 1 trillion atoms

Answer 1

A pure substances can not be decomposed into two other pure materials so, option (E) is correct A^+ is a positive ion. It is missing electron