24 Questions
What happens to chromium in the presence of atmospheric oxygen?
It gets partly or wholly oxidized to the tervalent state
Which type of ions does chromium form in aqueous solutions?
Cr2+, Cr3+ cations, and chromate (CrO4) 2- anions
Which ion complex is present in the 'green' solutions of chromium (III)?
[Cr(H2O)5CI]2+
Why are Cr2+ ions rarely encountered in inorganic qualitative analysis?
They decompose even in water slowly with hydrogen formation
What is the color of the solutions where the hexaquochromate (III) ion is present?
Violet
How does dilute sulfuric acid react with chromium?
Attacks chromium slowly with the formation of hydrogen gas
What happens when aluminum objects are exposed to air?
They form a protective oxide layer on the surface.
How does concentrated HCl react with aluminum?
Dissolves aluminum with the evolution of hydrogen gas.
What is the valence of chromium in chromic compounds?
+3
Which statement about aluminum sulfide is correct?
It forms in attractive crystal shapes.
What is the effect of adding some mercury (II) chloride to the mixture of aluminum and acid?
Speeds up the dissolution process.
Which compound is formed when Manganese reacts with warm water?
Mn(OH)2
What happens when hot, concentrated H2SO4 attacks Manganese?
Sulfur dioxide is evolved
Which characteristic describes chromium (Cr3+)?
Seldom seen in the free state.
Which color do the Mn(II) salts appear to be in solutions?
Pink
What type of ions does aluminum form with alkali hydroxides?
[Al(OH)4] - ions
How many oxides of manganese are known?
Six
What do Mn(II) cations derive from?
Manganese oxide (MnO)
Which statement about manganese compounds is correct?
Mn(VII) compounds contain the permanganate ion (MnO4-)
What is the correct statement about zinc's physical properties?
Zinc melts at 410°C and boils at 906°C
Which statement about zinc's reactivity with acids is incorrect?
Zinc dissolves in very dilute HNO3 without gas evolution
What happens when zinc reacts with hot, concentrated H2SO4?
Sulfur dioxide gas is evolved
Which statement about zinc's reaction with alkalis is correct?
Zinc dissolves in alkali hydroxides, forming tetrahydroxozincate(II), [Zn(H2O)4]2-
What are the applications of metallic zinc mentioned in the text?
Making brass and galvanizing iron
Test your knowledge on the properties of aluminum including its color, melting point, reaction with acids, and oxide layer formation when exposed to air.
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