Water - Jamb Chemistry Past Questions and Answers

Question 16:

• JAMB 1984

Water is said to be 'hard' if it

A. Easily forms ice
B. Has to be warmed before sodium chloride dissolves in it
C. Froms an insoluble scum with soap
D. Contains nitrates
E. Contains sodium ions

Question 17:

• JAMB 1984

The solubility curves of four substances are shown in the figure above. Which of the four substances would crystallize from a saturated solution cooled from 353K(80^oC)to 323K(50[sup][/sup]C)?

A. P and Q
B. P and R
C. P and S
D. R and S
E. Q and R

Question 18:

• JAMB 1985

Addition of dilute hydrochloride acid to an aqueous solution of a crystalline salt yield a yellow precipitate and a gas which turned dichromate paper green. The crystalline salt was probably?

A. Na₂SO₄
B. Na₂S
C. Na₂S₂O₃.5H₂O
D. Na₂CO₃
E. NaHCO₃

Question 19:

• JAMB 1988

The forces holding naphthalene crystals together can be overcome when naphthalene is heated to a temperature of 354K resulting in the crystal to melting. These forces are known as?

A. Coulombic
B. Ionic
C. Covalent
D. Van der waals

Question 20:

• JAMB 1988

The molar ratio of oxygen to nitrogen in dissolved air is 2:1 whereas the ratio is 4:1 in atmospheric air because?

A. Nitrogen is less soluble than oxygen
B. Oxygen is heavier than nitrogen
C. Nitrogen has a higher partial pressure in air
D. Gases are hydrated in water