In the preparation of some pure crystals of Cu (NO₃)₂ starting with CuO, a student gave the following statements as steps he employed. Which of these shows a flaw in his report ?

A. some CuO was reacted with excess dilute H₂SO₄

B. the solution was concentrated

C. when the concentrate was cooled, crystals formed were removed by filtration

D. the crystals were washed with very little cold water

E. the crystals were then allowed to dry

Which of the following separation processes is most likely to yield high quality ethanol (>95%) from palm wine?

A. Fractional distillation without a dehydrant

B. simple distillation with a dehydrant

C. fractional distillation with a dehydrant

D. column chromatography

E. evaporation

Increasing the pressure of a gas

A. lowers the average kinetic energy of the molecules

B. decreases the density of the gas

C. decreases the temperature of the gas

D. increases the density of the gas

E. increases the volume of the gas

2.5 g of a hydrate barium salt gave on heating, 2.13 g of the anhydrous salt. Given that the relative molecular mass of the of the anhydrous salt is 208, the number of molecules of water of crystallization of the barium salt is

A. 10

B. 7

C. 5

D. 2

E. 1

3. 06 g of a sample of potassium trioxochlorate (V) (KCIO\(_3\)) was required to make a saturated solution with 10cm\(^3\) of water at 25°C. The solubility of the salt at 25°C is [K =39, Cl = 35.5, O = 16]

A. 5.0 moles dm³

B. 3.0 moles dm³

C. 2.5 moles dm³

D. 1.0 molesv

E. 0.5 moles dm³

The cracking process is very important in the petroleum industry because it.

A. gives purer products

B. yields more lubricants

C. yields more engine fuels

D. yields more asphalt

E. yields more candle wax

A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is

A. O₂

B. NO

C. SO₂

D. NH₃

E. CO₂

Which of the following solutions will give a white precipitate with barium chloride solution and a green flame test?

A. Na₂SO₄

B. CuSO₄

C. CaSO₄

D. CaCI₂

E. (NH₄)₂SO₄

The mass of an atom is determined by

A. its ionization potential

B. its electrochemical potential

C. the number of protons and electrons

D. the number of neutrons and protons

E. the number of neutrons and electrons

Which of the following is a neutralization reaction?

A. Addition of sodium chloride solution to potassium chloride solution

B. Addition of trioxonitrate (V) acid (nitric acid) to distilled water

C. Addition of trioxonitrate (V) acid (nitric acid) to tetraoxosulphate (IV) acid (sulphuric acid)

D. Addition of trioxonitrate (V) acid (nitric acid) to potassium trioxonitrate (V) (potassium nitrate) solution

E. Addition of trioxonitrate (V) acid (nitric acid) to potassium hydroxide solution