WAEC 2026 CHEMISTRY ANSWER


CHEMISTRY OBJ ANSWER










(1ai)
Suspension:
(PICK ANY ONE)
-Muddy water
-Sand in water
-Flour in water

(1aii)
Colloid:
(PICK ANY ONE)
-Milk
-Starch solution
-Fog
-Smoke
-Gelatin

(1b)
(PICK ANY ONE)
An isoelectronic series is a group of atoms or ions having the same number of electrons and the same electronic configuration.

OR

An isoelectronic series is a group of atoms, ions, or molecules that contain the same number of electrons but have different nuclear charges (different numbers of protons).

(1ci)
Heat of formation:
The heat change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

(1aii)
Heat of combustion:
The heat evolved when one mole of a substance is completely burnt in excess oxygen under standard conditions.

(1d)
(PICK ANY ONE)
Helium is preferred to hydrogen because it is chemically inert and non-flammable. Whereas hydrogen is highly flammable and can form explosive mixtures with air. Therefore, helium is safer to use.

OR

Helium is preferred to hydrogen because it is a noble gas and is chemically inert, so it does not react readily and is non-flammable. Hydrogen, on the other hand, is highly flammable and can form explosive mixtures with air.

(1e)




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(4ai)
(PICK ANY ONE)
Hydrogen gas is tested by bringing a lighted splint to the mouth of the container holding the gas. The gas burns with a characteristic squeaky pop sound, confirming the presence of hydrogen.

OR

Bring a lighted splint to the mouth of a container containing the gas. If the gas is hydrogen, it burns with a 'pop' sound.

(4aii)
(PICK ANY THREE)
(i) It is used in the manufacture of ammonia by the Haber process.
(ii) Hydrogenation of vegetable oils to make margarine.
(iii) It is used as a fuel (e.g., rocket fuel/fuel cells).
(iv) Oxy-hydrogen flame for welding and cutting metals.
(v) It is used in the preparation of hydrochloric acid.

(4aiii)



(4ciii)
Water gas

(4di)
(I) Tin:
Reduction of its oxide with carbon (smelting).

(II) Iron:
Reduction of its oxide with carbon monoxide in the blast furnace.

(III) Aluminium:
Electrolysis of purified alumina dissolved in molten cryolite.

(4dii)
(PICK ANY ONE)
(i) It is used in the manufacture of aircraft bodies.
(ii) It is used in the manufacture of cooking utensils .
(iii) It is used in the manufacture of overhead electrical cables.
(iv) It is used in the manufacture of roofing sheets.

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(5)