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Chemistry Past Questions and Answers

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Chemistry Questions

Question 2841:

What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?

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A 15
B 30
C 35
D 50

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Question 2842:

Which of the following sets of elements are arranged in order of decreasing atomic size in the Periodic Table?

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A <sub style='font-size: smaller;'>6</sub>C, <sub style='font-size: smaller;'>4</sub>Be, <sub style='font-size: smaller;'>7</sub>N,<sub style='font-size: smaller;'>8</sub> O
B <sub style='font-size: smaller;'>4</sub>Be,<sub style='font-size: smaller;'>6</sub> C,<sub style='font-size: smaller;'>7</sub> N,<sub style='font-size: smaller;'>8</sub> O
C <sub style='font-size: smaller;'>8</sub>O, <sub style='font-size: smaller;'>7</sub> N, <sub style='font-size: smaller;'>6</sub>C, <sub style='font-size: smaller;'>4</sub>Be
D <sub style='font-size: smaller;'>7</sub>N, <sub style='font-size: smaller;'>8</sub>O, <sub style='font-size: smaller;'>6</sub>C,<sub style='font-size: smaller;'>4</sub>BeBe

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Question 2843:

Which of the following changes is characteristic of an alpha-particle emission?

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A The nucleus loses two protons and two neutrons
B A proton combines with an electron giving off heat
C The nucleus splits into two equal parts
D Four neutrons are lost

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Question 2844:

An element X has an atomic number of 16. What is its most likely oxidation state in its binary compounds?

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A -3
B -2
C +2
D +4

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Question 2845:

An element which can exist in two or more forms in the same physical state, exhibits

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A Isotopy
B Structural isomerism
C Allotropy
D Variable valency

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