Question 421:

• JAMB 1985

The atomic number of an element whose cation, X²⁺, has the ground state electronic configuration 1s²2s²2p⁶3s²2p⁶ is?

A. 16
B. 18
C. 20
D. 22
E. 24

Question 422:

• JAMB 1985

When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains?

A. NaOH
B. KOH
C. Mg(OH)₂
D. Zn(OH)₂
E. Ca(OH)₂

Question 423:

• 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 424:

• JAMB 1985

The process involved in the conversion of an oil into margarine is known as?

A. Hydrogenation
B. Condensation
C. Pyrolysis
D. Dehydration
E. Cracking

Question 425:

• JAMB 1985

An aqueous solution of an inorganic salt gave white precipitate (i) soluble in excess aqueous NaOH (ii) insoluble in excess aqueous NH₃ (iii) with dilute HCl. The cation present in the inorganic salt is?

A. Na₄⁺
B. Ca⁺⁺
C. Zn⁺⁺
D. Al⁺⁺⁺
E. Pb₊₊