MCQs — Electrochemistry

Practice questions for Chemistry.

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Question 81

Combining Ca2+ and Cl- ions in the simplest neutral ratio gives the formula:

A. CaCl

B. CaCl2

C. Ca2Cl

D. CaCl3

Question 82

Combining Mg2+ and O2- ions in the simplest neutral ratio gives the formula:

A. MgO2

B. Mg2O

C. MgO

D. Mg2O2

Question 83

Magnesium oxide has a simple 1:1 ratio of ions, unlike calcium chloride, because:

A. Magnesium's 2+ charge and oxide's 2- charge already balance each other exactly with just one ion of each

B. Magnesium never actually forms a charged ion

C. Oxide ions always outnumber metal ions in every compound

D. This ratio is simply a historical convention with no charge basis

Question 84

Aluminium sulphate requires two aluminium ions for every three sulphate ions because:

A. Aluminium forms a 3+ ion and sulphate forms a 2- ion, and the smallest whole-number ratio that balances total charge is 2 aluminium ions to 3 sulphate ions

B. Aluminium and sulphate always combine in a 1:1 ratio

C. Sulphate ions carry no charge at all

D. This ratio has no relation to ionic charge

Question 85

Combining Al3+ and SO4^2- ions in the simplest neutral ratio gives the formula:

A. AlSO4

B. Al2SO4

C. Al2(SO4)3

D. Al3(SO4)2

Question 86

When writing the formula of an ionic compound, parentheses are placed around a polyatomic ion mainly when:

A. The polyatomic ion is negatively charged

B. More than one of that polyatomic ion is needed to balance the charges

C. The compound is a gas at room temperature

D. The polyatomic ion contains oxygen

Question 87

Parentheses are necessary around a polyatomic ion's formula when a subscript greater than one is needed because:

A. Without parentheses, the subscript would appear to apply only to the last atom in the polyatomic ion, rather than to the entire ion

B. Parentheses are purely decorative and carry no real meaning

C. Polyatomic ions cannot otherwise be written at all

D. This notation is required only for cations, never anions

Question 88

Roman numerals are used in the names of some ionic compounds mainly to indicate:

A. The compound's physical state

B. The oxidation state (charge) of a metal that can exhibit variable oxidation states

C. The number of moles of the compound present

D. The compound's melting point

Question 89

Roman numerals are typically needed when naming compounds of which category of metals?

A. Group IA (alkali metals), since they always have variable charges

B. Transition metals, since they commonly exhibit variable oxidation states

C. Noble gases, since they form many different ions

D. Group IIA metals only

Question 90

The compound CuSO4 is named, using a Roman numeral, as:

A. Copper(I) sulphate

B. Copper(II) sulphate

C. Copper(III) sulphate

D. Copper(IV) sulphate

Question 91

The compound FeCl2 is named, using a Roman numeral, as:

A. Iron(I) chloride

B. Iron(II) chloride

C. Iron(III) chloride

D. Iron(IV) chloride

Question 92

The compound FeCl3 is named, using a Roman numeral, as:

A. Iron(I) chloride

B. Iron(II) chloride

C. Iron(III) chloride

D. Iron(IV) chloride

Question 93

Both FeCl2 and FeCl3 need Roman numerals in their names, while a compound like NaCl does not, because:

A. Iron can form more than one stable oxidation state (+2 and +3), so the Roman numeral distinguishes which compound is meant, whereas sodium only forms one common oxidation state

B. Iron never actually forms a charged ion

C. Sodium chloride does not actually contain any ions

D. Roman numerals are simply optional stylistic choices with no real function

Question 94

If a metal always exhibits exactly the same, single oxidation state in all of its compounds, would a Roman numeral generally be considered necessary in its compound names?

A. Yes, Roman numerals are always required for every metal

B. No, since a Roman numeral is only needed to distinguish between multiple possible oxidation states

C. Only if the metal is a transition metal

D. Only if the compound is a solid

Question 95

A metal forms Fe2+ in one compound and Fe3+ in another, both combined with chloride ions. The correct Roman-numeral names for these two compounds (FeCl2 and FeCl3) are, respectively:

A. Iron(III) chloride and iron(II) chloride

B. Iron(II) chloride and iron(III) chloride

C. Iron chloride and iron dichloride

D. Ferrous(II) and ferric(III) chloride, with no distinction needed

Question 96

An oxidizing agent is best defined as a substance that:

A. Causes another substance to be reduced by donating electrons to it

B. Causes another substance to oxidize by taking electrons from it

C. Never participates in any electron transfer

D. Is always a metal

Question 97

An oxidizing agent is often called an electron acceptor because it:

A. Donates electrons during a reaction

B. Accepts electrons during a reaction

C. Never gains or loses electrons

D. Only accepts protons

Question 98

A reducing agent is best defined as a substance that:

A. Causes another substance to oxidize by taking electrons from it

B. Causes another substance to be reduced by donating electrons to it

C. Never participates in any electron transfer

D. Is always a non-metal

Question 99

A reducing agent is often called an electron donor because it:

A. Accepts electrons during a reaction

B. Loses (donates) electrons during a reaction

C. Never gains or loses electrons

D. Only donates protons

Question 100

Oxidizing agents themselves become reduced during a reaction, while reducing agents themselves become oxidized, because:

A. An oxidizing agent gains the electrons it takes from another substance (so it is reduced), while a reducing agent loses the electrons it donates (so it is oxidized)

B. Oxidizing and reducing agents never actually undergo any change themselves

C. Both agents always lose electrons simultaneously

D. This naming is arbitrary and has no connection to electron transfer

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