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Chemistry Past Questions and Answers

Waec Chemistry Questions

Question 256:

Carbon is often deposited in the exhaust-pipe of cars because of the

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A Presence of carbon in petrol
B Dehydrogenation of petrol
C Incomplete combustion of petrol
D Presence of additives in petrol
E Contamination of petrol with diesel

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Question 257:

What does X atand for in the following expression? X = Log₍₁₀₎(H⁺)

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A Enthalpy change (âˆ†H)
B Equilibrium constant (K)
C Solubility product
D Degree of acidity (pH)
E Lonic product of water

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Question 258:

Sulphur burns in air to form

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A An acidic oxide
B A basic oxide
C An amphoteric oxide
D A neutra oxide
E A mixed oxide

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Question 259:

In which of the following changes is âˆ†S negative ?

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A H₂O_(l) â†’ H₂O_(s)
B C_(s) + 1/2O_{2,/sub>[sub](g)} → CO_(g)[/sub]
C PCI₅_(g) â†’ PCl₃_(g) + Cl₂_(g)
D NaCl_(s) + aq â†’Na₊_(aq) + Cl_-_(aq)
E NH₃_(g) + HCl_(g)

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Question 260:

Chlorine is is used in water treatment as

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A A germicide
B A decolorizing agent
C An antioxidant
D A coagulating agent
E An aerating agent

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