Page 433 - SUBSEC October 2017_Neat

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Item 25 refers to the diagram below which shows a double beam instrument used
in spectroscopic analysis of liquid/solution.

25. What is the name of the device labelled I?

(A) Grating
(B) Photodetector
(C) Shutter
(D) Monochromator

Item 26 refers to the following information.

Hydrogen bromide undergoes fragmentation when passed into a spectrometer. Bromine has two
isotopes, Br−79 and Br−81. The hydrogen involved here has only isotope. The spectrum is given
below.

26. Which of the following combinations of ionic isotopes is responsible for the peaks at mass 79,
80, 81 and 82?

(A) A
(B) B
(C) C
(D) D

27. Which of the following atomic nuclei pairs both have nuclear spin?

(A) 2 H and C
13
(B) 1 H and Mg
24
(C) 19 F and Na
23
(D) 32 P and p
31

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