$CATEGORY: Science - TicTacLearn/3. Atoms and molecules/3. Atoms and molecules--Writing Chemical Formulae 

//Multiple Choice

The symbolic representation of compositions of the compound is called\:
{
~Chemical reaction
~Chemical bond
=Chemical formulae
~Chemical equation
}

What is the valency hydrogen ion (H+)?
{
~2
=1
~3
~4
}

Choose the odd one based on valency\:
{
~Potassium ion
~Chloride ion
=Calcium ion
~Hydroxide ion
}

Which of the following represents the chemical formula for sulfuric acid?
{
~H₂SO₄
~H₂SO₃
~SO₃
=HSO₄
}

Which of the following elements has a valency of 3?
{
~Sodium
~Oxygen
=Aluminum
~Potassium
}

What is the chemical formula of calcium oxide?
{
=CaO
~Ca2O
~CaO2
~CaO3
}

What is the valency of nitrogen in ammonia (NH₃)?
{
~2
~5
~4
=3
}

In NaCl, the valency of sodium is\:
{
~0
=1
~4
~2
}

What does a chemical formula represent?
{
~Only the number of molecules
~Only the type of elements
=The types and ratios of atoms in a compound
~The physical state of a compound
}

Which rule must be followed when writing the formula for compounds with polyatomic ions?
{
~Always use brackets
=Use brackets when a polyatomic ion appears more than once
~Use brackets around monatomic ions
~Use brackets around single atoms
}

What is the chemical formula of calcium hydroxide?
{
~\(CaOH\)
~\(CaOH_2\)
=\(Ca(OH)\)\(_2\)
~\(Ca(OH)\)\(^2\)
}

How many polyatomic ions are present in the sodium hydroxide?
{
~2
=1
~3
~4
}

What is the chemical formula for water?
{
=H₂O
~H₂O₂
~HO₂
~OH
}

How many atoms are present in a molecule of H₂O?
{
~1
~4
=3
~5
}

What does the subscript “2” in H₂ represent?
{
=Two hydrogen atoms
~Two hydrogen molecule
~Two water molecules
~Two oxygen atoms
}

Which rule should be followed when writing chemical formulae of compounds?
{
~The more electronegative element is written first.
~Subscripts are ignored.
=The metal is written first, followed by the non-metal.
~The least reactive element is written first.
}


//True or False

The calcium is represented by the chemical symbol “C”.{F}

The combining capacity of an element is known as its valency.{T}

The valency or charges on the ion must be balanced while writing a chemical formula.{T}

Brackets are necessary when writing the chemical formula of a compound containing polyatomic ions with a valency of 1.{F}

The hydrogen sulfide is a binary compound.{T}

The anions have a negative charge on them.{T}

We do not use brackets when there is only one ion present in a compound containing polyatomic ions.{T}

The valency of hydrogen is always 1.{F}

HCl contains a polyatomic ion.{F}

A compound’s chemical formula gives information about both the elements and the number of atoms in each element present in the compound.{T}

The charges on the ions are indicated in a chemical formula.{F}

The magnesium chloride has two chloride ions.{T}


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