The pair of metals in the reactivity series that are usually extracted by the electrolysis of their ores is
A. magnesium and zinc
B. magnesium and calcium
C. copper and zinc
D. lead and calcium

What properties of duralumin make it more useful than its constituent metals?
A. It is heavy with a high melting point
B. It is malleable and has high density
C. It is strong and light
D. It is hard and ductile

Hydrogen is used in oxy-hydrogen flames for melting metals because it
A. evolves a lot of heat when burnt
B. combines explosively with oxygen
C. is a very light gas
D. is a rocket fuel

A pair of compounds that can be used to generate a gas which has physiological effect on human beings is

A. sodium trioxonitrate (V) and calcium chloride
B. sodium dioxonitrate (III) and ammonium chloride
C. sodium trioxonitrate (V) and ammonium chloride
D. sodium dioxonitrate (III) and potassium chloride

The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is
A. Na2SO4
B. Na2SO3
C. Na2S
D. Na2CO3

Chlorine, bromine and iodine resemble one another in that they?

A. dissolve in alkalis
B. react violently with hydorgen without heating
C. are liquids
D. displace one another from solutiions of their salts

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The gas that will form a white precipitate with acidified silver trioxonitrate (v) is
A. NH3
B. SO2
C. CO2
D. HCL

Which of the following statement is true of the electrochemical series?
A. Electropositivity of metals increase down the series
B. Electropositivity of non-metals decrease down the series
C. Electronegativity of non-metals decrease down the series
D. Electropositivity of metals decreases down the series

69
RS(aq) + HF(aq) → RF(s) + HS(aq)
ΔH = -65.7 kj mol(-1).
From the equation above, it can be deduced that
A. the heat content of the reactants is lower than that of the products
B. the heat content of the reactants is higher than that of the products
C. the reaction is slow
D. a large amount of heat is absorbed