Which of the following samples will react fastest with dilute trioxonitrate (V) acid?

• A. 5 g of lumps of CacO₃ at 25°C
• B. 5 g of powered CacO₃ at 25°
• C. 5 g of lumps of CaCO₃ at 50°C
• D. 5 g of powered CaCO₃ AT 50°C

An orange drink concentrate is suspected to contain traces of poisonous green dye and a harmless dye having the same boiling point. Which of the following techniques is most suitable for isolating the dyes?

• A. Fractional distillation
• B. Paper chromatography
• C. Coagulation
• D. Recrystallization

Which of the following devices function on redox reaction? l. Dry cell ll. Car battery III. Electric generator

• A. l and lll only
• B. ll and lll only
• C. l and ll only
• D. l, ll and lll

(a) Name the residue obtained on strongly heating the following:

(i) ZnCO\(_3\) in an open crucible;

(ii) CuSO\(_4\), 5H\(_2\)O and then allowing it to cool in a desiccator.

(b) State the colour changes observed on heating and cooling in each case in(a) above.

16.55g of lead (ll) trioxonitrate (V) was dissolved in 100g of distilled water at 20oC, calculate the solubility of the solute in moldm-3 [Pb = 207, N = 14, O = 16]

• A) 0.05 g
• B) 2.00 g
• C) 1.00 g
• D) none of the above

On cracking medicinal paraffin, a gas is evolved which gives a pop sound with a lighted splinter and an oily liquid which decolourizes bromine solution is also obtained. The products of the cracking are ?

• A. carbon (IV) oxide and alkyne
• B. carbon (ll) oxide and alkene
• C. hydrogen gas and alkene
• D. hydrogen gas and alkane

The electron configuration of \(_{22}X^{2+}\) ion is

• A)
  1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\)4s\(^2\)3d\(^2\)
• B)
  1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)4s\(^2\)3d\(^1\)
• C)
  Is\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\)
• D)
  1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\)4s\(^2\)

Which of the elements will burn in excess oxygen to form a product that is neutral to litmus?

• A. Carbon
• B. Hydrogen
• C. Sulphur
• D. Sodium

In which reaction will the point of equilibrium shift to the left when the pressure on the system is increased?

• A)
  C(s) + O\(_2\)(g) \(\iff\) CO\(_2\)(g)
• B)
  CaCO\(_3\)(s) \(\iff\) CaO(s) + CO\(_2\)(g)
• C)
  2Mg(s) + O\(_2\)(g) \(\iff\) 2MgO(s)
• D)
  2H\(_2\)(g) + O\(_2\)(g) \(\iff\) 2H\(_2\)O(g)

Hardness of water is mainly due to the presence of

• A) calcium hydroxide or magnesium hydroxide
• B) calcium trioxocarbonate (IV) or calcium tetraoxosulphate (VI)
• C) sodium hydroxide or magnesium ydroxide
• D) calcium chloride or sodium chloride salts