IGCSE Chemistry Paper-1: Specimen Questions with Answers 37 - 39 of 99
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Question 37
Question
MCQ▾The red colour in some pottery glazes may be formed as a result of the reactions shown.
CuO + SnO ⇾ Cu + SnO2
CuCO3 ⇾ CuO + CO2
These equations show that … 1 … is oxidised and … 2 … is reduced. Which substances correctly complete gaps 1 and 2 in the above sentence?
Choices
| Choice (4) | |
|---|---|
a. | 1 = CuO 2 = SnO |
b. | 1 = CuCO3 2 = CuO |
c. | 1 = CO2 2 = SnO2 |
d. | 1 = SnO 2 = CuO |
Answer
d.Explanation
Oxidation means gain of oxygen and reduction means loss of oxygen.
CuO + SnO ⇾ Cu + SnO2
In the above reaction we can see that CuO turns into Cu (i.e.. loss of oxygen) . Hence it is a reduction reaction whereas SnO turns to SnO2 (i.e.. gain of oxygen) therefore an oxidation reaction.
Question 38
Question
MCQ▾Element X has a nucleon number of 19 and a proton number of 9.
Which group in the Periodic Table does it belong to?
Choices
| Choice (4) | |
|---|---|
a. | VIII |
b. | III |
c. | I |
d. | VII |
Answer
d.Explanation
Given, Proton number/Atomic number of element = 9
Electronic configuration of the element will be 1s2 2s2 2p5
Since last sub shell is p group is group is A
Adding 2 + 5 = 7
Therefore group will be 7A
Question 39
Question
MCQ▾What explains combination reaction?
Choices
| Choice (4) | |
|---|---|
a. | Zn (s) + CuSO4 (aq) ⇾ ZnSO4 (aq) + Cu (s) |
b. | AgNO3 (aq) + NaCl (aq) ⇾ AgCl (s) + NaNO3 (aq) |
c. | C (s) + O2 (g) ⇾ CO2 (g) |
d. | All of the above |
Answer
c.Explanation
A combination reaction is a reaction in which two reactants combine to form one product. Oxygen and the halogens are very reactive elements and are likely to undergo combination reactions with other elements. In the above example carbon combines with oxygen to form carbon dioxide.