QUESTION 3   Substances can be elements, compounds or…

QUESTION 3   Substаnces cаn be elements, cоmpоunds оr mixtures.   а Which of these is a correct symbol for an element?      A   Fe    B   O2    C   H2O    D   H2O2 (1) b Which of these substances is a compound?      A   brass    B   helium    C   oxygen    D   water (1) c Which substance is a mixture                                                                                                                                                                                                    A   gold    B   hydrogen gas    C   air    D   water (1) d Paper chromatography is used to separate the dyes present in some inks.   A sample of ink, P, is spotted on to some chromatography paper. Four known inks, A, B, C and D, are also spotted on to the same paper.   The diagram (see the diagram pdf)shows how the experiment is set up and the paper at the end of the experiment.   d(i) State why the solvent level should not be above the base line at the start of the experiment. (1) d(ii) Explain which dye, present in one of the inks A, B, C or D, is also present in ink P. (2) d(iii) State why ink D does not move during the experiment. (1) d(iv) Dyes have an Rf value that can be calculated using the below expression.   Rf =   Complete the below table for the dye in ink B.   Distance moved by the dye in ink A in mm. Distance moved by solvent in mm. Rf value of dye in ink A. (2) e The diagram (see the diagram pdf) shows an experiment to demonstrate diffusion.   e(i) The word equation for the reaction that occurs in this experiment is   ammonia + hydrogen chloride → ammonium chloride   Complete the chemical equation for this reaction.   NH3 + HCl → ................................................ (1) e(ii) State the two state symbols that could be included in the chemical equation in part (e)(i).   s       g       l       aq (1)