IGCSE Chemistry Paper-1: Specimen Questions with Answers 40 - 41 of 99
Question number: 40
Question
The diagram shows the positions of elements L, M, Q, R and T in the Periodic Table. These letters are not the chemical symbols of the elements.
Define Characteristics of Elements L, M, Q, R and T in Table.
Find special characteristics of elements L, M, Q, R and T
Which statement about the properties of these elements is correct?
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | L, M and Q are all metals. |
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| b. | L reacts more vigorously with water than does M. |
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| c. | T exists as diatomic molecules. |
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| d. | T is more reactive than R. |
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Answer
a.Explanation
The above diagram shows that
- L and M belongs to group 1 (alkali metals)
- Q belongs to group 3 (Lanthanides)
Metals comprise the large majority of the elements, and can be subdivided into several different categories. From left to right in the periodic table, these categories include the highly reactive alkali metals; the less reactive alkaline earth metals, followed by lanthanides.
Metals form mixtures when combined with other metals and tend to lose or share electrons when they react with other substances; and each forms at least one predominately basic oxide.
Question number: 41
Question
The table shows the structure of different atoms and ions.
| particle | proton | nucleon | number of | number of | number of |
| number | number | protons | neutrons | electrons | |
| Mg | 12 | 24 | 12 | W | 12 |
| Mg2+ | X | 24 | 12 | 12 | 10 |
| F | 9 | 19 | 9 | Y | 9 |
| F– | 9 | 19 | 9 | 10 | Z |
What are the values of W, X, Y and Z?
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | W = 10 X = 10 Y = 9 Z = 9 |
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| b. | W = 12 X = 10 Y = 9 Z = 10 |
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| c. | W = 10 X = 12 Y = 10 Z = 9 |
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| d. | W = 12 X = 12 Y = 10 Z = 10 |
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Answer
d.Explanation
- X = No. of neutrons = Nucleon no. – proton no
= 24 - 12 = 12
- . All atoms of the same element have same number of protons. The 2 + charge means there’s 2 fewer electrons than there are protons.
- Therefore, Y = 12
- Y = No. of neutrons = Nucleon no. – proton no
= 19 - 9 = 10
Z = No of electrons = no of protons
= 9 + 1 (for the negative charge) = 10