2018 - JAMB Chemistry Past Questions and Answers - page 6
The refreshing and characteristic taste of soda water and other soft drinks is as a result of the presence of
Which of the following are mixtures?
I. Petroleum
II. Rubber latex
III. Vulcanizer's solution
IV. Carbon sulphide
A balanced chemical equation obeys the law of
When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;
This is because the quick-lime acts as a drying agent hence, it can dry most gases except ammonia. Consequently, it removes the water vapour. Quick-lime (calcium oxide) reacts with the carbon dioxide forming calcium carbonate. Carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases.
In the laboratory preparation of oxygen, the gas cannot be collected by displacement of air because
2KClO3(g) MNO3→ 2KCl(s) + 3O2(g)
The importance of the catalyst in the reaction above is that
A catalyst is a substance that speeds up a chemical reaction, but is not consumed by the reaction.
Which of the following is used to power steam engines?
The setup could go like this:
A fire where the coal burns. A boiler full of water that the fire heats up to make steam. A cylinder and piston, rather like a bicycle pump but much bigger. Steam from the boiler is piped into the cylinder, causing the piston to move first one way then the other.
Ref.In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?
2NaOH + H\(_2\) SO\(_4\)↔Na\(_2\)SO\(_4\) + 2H\(_2\)O
V x 0.5M = 2(10 x 1.25)
0.5V = 2 x 12.5
0.5V = 25
V = 250.5 = 50cm\(^2\)
To what volume must 300cm\(^3\) of 0.60M sodium hydroxide solution be diluted to give a 0.40M solution?
From the dilution law:
C\(_1\)V\(_1\) = C\(_2\)V\(_2\)
C\(_1\) = Initial conc. of NaOH = 0.6M
V\(_1\) = Initial Volume of NaOH = 300cm3
C\(_2\) = Final conc. of NaOH = 0.4M
V\(_2\) = Final Volume of NaOH = ?
V\(_2\) = \(\frac{C_1V_1}{C_2}\)
V\(_2\) = \(\frac{0.6 \times 300}{0.4}\)
V\(_2\) = 450 cm\(^3\)
Diamond is a bad conductor of electricity because its bonding electrons are used in
Diamond is a covalent macromolecule, and typical of a covalent substance is an insulator. All valence electrons are localized in well-defined covalent bonds and hence are not free to move through the structure