chemistry

Topics: Chemical element, Atomic number, Atomic mass Pages: 7 (1050 words) Published: March 17, 2014
Candidate name……………………………………………………………………..

MINISTRY OF EDUCATION
MASALA SECONDARY SCHOOL BOARD MOCK EXAMINATION 2014
SCIENCE5124/3
PAPER 3 (CHEMISTRY)1hour 15minutes
Additional materials:Monday 30th July 2014.
Answer paper
INSTRUCTIONS TO CANDIDATES
Write your name, centre number and candidate number at the top of this page all separate Attempt all questions in SECTION A and only TWO questions in SECTION B SECTION A (45 marks)
Answer all question in this section in the spaces provided Q1 Forensic scientists use paper chromatography to compare the inks from five different bank notes with the ink used to make legal bank notes. The results are shown as a chromatogram in Fig. 4.1.

(a) Draw the apparatus that could be used to produce this chromatogram.

(b) Which of the bank notes F, G, H, I and J

(i) is not a forgery,
................................................................... (ii) are printed with identical inks,
................................................................... (iii) is printed with ink containing four solvent-soluble dyes? ................................................................... [3] (c) Use your knowledge of bank notes to suggest why water would probably not be a suitable solvent to use for this chromatography.

.......................................................................................................................................... ...................................................................................................................................... [1]

Q2 An atom has an atomic number of 17 and a relative atomic mass of 35.

(a) Determine the number of protons and neutrons in the nucleus of this atom

Protons -------------------------------------- neutrons -------------------------------------------- [2]

(b) Three members of the halogens are 
(i) Draw the electron structure of an atom of chlorine.

[1]

(ii) Why is the relative atomic mass of chlorine not a whole number? ……………………………………………………………………………………………… ……………………………………………………………………………………………[1] (iii) How many electrons are in the highest energy levels of chlorine? ……………………………………………………………………………………………… …………………………………………………………………………………………... [1] Q3. The electronic structure of a sulphur atom can be written as 2, 8, 6. (a) Write, in this way, the electronic structures of the atom of carbon and oxygen. ………………………………………………………………………………………………………………………………………………………………………………………………………………… [1] (b) Draw the diagram showing the electron arrangement in a molecule of CO2.

[2]
(c) Explain why pure CO2 cannot normally conduct electricity.

………………………………………………………………………………………………….. …………………………………………………………………………………………………... [2]
Q 4 Vanadium, V, is extracted from a mineral called vanadinite. The chemical formula of vanadinite is shown below.

Pb5(VO4)3Cl

(a) Calculate the relative molecular mass of vanadinite. [1]

[Relative atomic masses: Ar: O, 16; Cl, 35.5; V, 51; Pb, 207]

(b) In the extraction process, vanadinite is converted into vanadium (III) chloride; VCl3.This is reduced at a very high temperature by magnesium to form metallic vanadium...
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