CIE Chemistry Paper-1: Specimen Questions 3 - 5 of 99
Question number: 3
An aqueous solution of the organic compound methylamine has a pH > 7. What can be said?
It neutralises an aqueous solution of sodium hydroxide.
It reacts with hydrochloric acid to form a salt.
It reacts with copper (II) carbonate to give carbon dioxide.
It turns blue litmus red.
pH greater then 7 means that the solution is either basic or alkaline in nature. When methylamine reacts with HCL, following reaction takes place:
H3CNH2 + HCl – > H3CNH3+ Cl
H3CNH3 formed in the reaction is known as N-methyl ammonium chloride, which is a salt.
Question number: 4
Which statement will be true in regard to phosphorus (P, atomic no = 15) and Arsenic (As atomic no = 33):
Phosphorus is more electronegative then Arsenic.
|b.||Arsenic is more electronegative then Phosphorus.|
They will have same amount of electronegativity
|d.||None of the above|
Phosphorus is more electronegative then Arsenic. On moving down in a group, the number of shell increases and the valance electrons move away from the nucleus and the effective nuclear charge decreases. This decreases the attraction between the nucleus and the electrons hence decreasing electronegativity.
Question number: 5
A mixture containing two anions was tested and the results are shown below.
If dilute nitric acid added then effervescence of a gas which turned limewater milky
If dilute nitric acid added, followed by aqueous silver nitrate then yellow precipitate is formed
Which anions were present?
carbonate and iodide
sulphate and chloride
carbonate and chloride
sulphate and iodide
For the test of carbonate ions:
- Limewater (aqueous calcium hydroxide) is used to identify carbonate ions in solution.
- Firstly a dilute acid is added to the solution. If carbonate ions are present carbon dioxide (CO2) gas will be given off.
- If carbon dioxide is passed through limewater a cloudy white precipitate of calcium carbonate will be formed.
For the test of iodide ions:
Add dilute nitric acid and silver nitrate solution. The silver nitrate is acidified with dilute nitric acid to prevent the precipitation of other non–halide silver salts. Yellow precipitate of silver iodide will be formed.
Ag+ (aq) + I– (aq) == > AgI (s) (Yellow Precipitate)