Selina solutions for Concise Chemistry [English] Class 6 ICSE chapter 4 - Elements, Compounds, Symbols And Formulae [Latest edition]

Classify the following substances into elements and compounds

Mercury, sulphur, sugar, water, sand, gold, carbon, oxygen, alcohol, iron, marble, baking soda.

Give the symbols of: Carbon, calcium, copper, chlorine, cobalt, argon. 

Define a pure substance. How many types of pure substances do you know?

Define Elements.

Define Compounds

Give two examples of Metals.

Give two examples of  Non-metals.

Give two examples of  Metalloids.

Give two examples of  Noble gases.

Name the elements which form water.
How will you justify that water is a compound? 

Give three differences between metals and non-metals.

How is sodium chloride different from its constituent elements, sodium and chlorine in its properties? Justify.

State four important characteristics of compounds

Give two examples of the following.

Non-metals which are solids

Give two examples of the following.
Metals which are soft

Give two examples of the following.
Non-metals which are lustrous

What is the proportion of element present in the following compound?
CaO 

Give two examples of the following.
Elements which are liquids

Give two examples of the following.
Inert gases

Give two examples of  Metalloids.

Name the elements present in Sugar

Name the elements present in Ammonia

Name the elements present in Marble

Name the elements present in Washing soda

What is the proportion of element present in the following compound?
H₂O

What is the proportion of element present in the following compound?
CO₂ 

What is the proportion of element present in the following compound?
NO₂ 

Name two compounds which dissolve in water.

Define: Atom 

Define: Molecule

Define:

Atomicity 

Define: Formula

Why are the symbols and formulae of substances important?

Mention three gaseous elements and write their molecular formulae

State the information obtained from the formula of a compound.

What is meant by 2H and H₂

What is meant by H₂0 and 3H₂O

State the number of atoms of C₆H₁₂O₆

State the number of atoms of H₂SO₄

State the number of atoms of each element, present in \[\ce{HNO3}\].

Also name the compound.

State the number of atoms of CaCO₃

Write the molecular formulae of compound calcium oxide.

Write the molecular formulae of compound hydrogen sulphide.

Write the molecular formulae of compound carbon monoxide

Write the molecular formulae of compound lead sulphide.

Name: Three different forms of carbon

Name: A form of carbon used as a gem

Name: Two substances used to make electric wires

Name: Two substances used to make jewellery.

Name A substance used as an insulator.

Give one use of the following substance:
Iron

Give one use of the following substance:
Brass

Give one use of the following substance:
Coal

Give reason: A frying pan is made up of steel but its handle is made up of wood.

Give reason: Graphite is used to make a lead of the pencils.

Give reason: Argon is filled in electric bulbs.

Answer the following question:
Why are copper and aluminium used to make electric wires?

Answer the following question:
What do you understand by the statement: ‘metals are ductile and malleable’?

Answer the following question:
Give the advantages of using symbols instead of names of elements or compounds.

Answer the following question:
When iron is mixed with sulphur at room temperature, it does not form a compound. Why?

Find the atomicity of the Following molecule:
Calcium Chloride

Find the atomicity of the Following molecule:
Aluminium Suiphide

Find the atomicity of the Following molecule:
Acetic Acid

Find the atomicity of the Following molecule:
Dinitrogen Oxide

Find the atomicity of the Following molecule:
Carbon Monoxide

Fill in the blank
_________ refers to the number of atoms in the molecule of an element

Fill in the blank
The most abundant element in the earth’s crust is _______.

Fill in the blank
A metal which is a liquid at room temperature is _______.

Fill in the blank
The most abundant element in the atmosphere is  _______.

Fill in the blank
A metal which is a poor conductor of electricity is  _______.

Fill in the blank
A diatomic gaseous element is _______.

Fill in the blank
A liquid non-metal is  _______.

Match the Columns:

Indicate whether the following statement is true or false:
A compound is made up of just one kind of atom

Indicate whether the following statement is true or false:
Metals reflect light and are good conductors of electricity

Indicate whether the following statement is true or false:
Metals can be polished.

Indicate whether the following statement is true or false:
Elements are made up of compounds

Indicate whether the following statement is true or false:
All elements are artificially prepared

Indicate whether the following statement is true or false:
Molecules can exist independently.

Indicate whether the following statement is true or false:
Molecules combine to form atoms

Indicate whether the following statement is true or false:
Noble gases are high reactive

Indicate whether the following statement is true or false:
Ozone is a triatomic molecule

Tick (√) the correct alternative from the choice given for the following statement.
All pure substances have

Tick (√) the correct alternative from the choice given for the following statement.
Sugar is a compound which consists of the elements

Tick (√) the correct alternative from the choice given for the following statement.
Atoms of different kinds combine to form molecules of

Tick (√) the correct alternative from the choice given for the following statement.
Sulphur and carbon are

Tick (√) the correct alternative from the choice given for the following statement.
Gold is used to make jewellery because

Tick (√) the correct alternative from the choice given for the following statement.
The most abundant elements in the universe are

Tick (√) the correct alternative from the choice given for the following statement.
The compound used as common salt is

Tick (√) the correct alternative from the choice given for the following statement.
Brass and bronze are

Tick (√) the correct alternative from the choice given for the following statement.
Sand is a compound of

Tick (√) the correct alternative from the choice given for the following statement

A metal which is brittle

Tick (√) the correct alternative from the choice given for the following statement

A non-metal which is a good conductor of electricity.

Tick (√) the correct alternative from the choice given for the following statement

The hardest naturally occurring substance

Tick (√) the correct alternative from the choice given for the following statement

The most ductile metal.

Tick (√) the correct alternative from the choice given for the following statement

A gaseous non-metal.

Classify substances into pure and impure substances in the form of a chart or tabulation.

Differentiate between the terms –
elements, compounds & mixtures.

The important physical properties of substances are colour, odour, nature, density & solubility in water.
Name – two coloured gases (with their colours)

The important physical properties of substances are colour, odour, nature, density & solubility in water.

Name – a gas with a pungent, choking odour which is lighter than air

The important physical properties of substances are colour, odour, nature, density & solubility in water.

Name - a poisonous gas almost as heavy as air.

Complete the statement – an element is a pure substance made up of ____________ atoms.

Draw a labelled diagram of an atom including its nucleus, orbits & their contents.

Elements are classified into – Metals – Non-metals – Metalloids – Noble gases. State which of A, B, C, D is a –

1. Metallic element
2. Non-metallic element
3. Metalloid
4. Noble gas.

A: Is non-malleable, non-ductile & a poor conductor of electricity ___________
B: Has lustre, is malleable and ductile & a good conductor of heat ___________
C: Is unreactive and inert and present in traces in the air _________
D: Shows properties of both metals and non-metals ___________

An atom of an element is denoted by a “symbol”. Explain the meaning of the term ‘symbol’. State a reason for representing the following element by its symbol.

Hydrogen by ‘H’

An atom of an element is denoted by a “symbol” Explain the meaning of the term ‘symbol’. State a reason for representing the following element by its symbol.

Helium by ‘He’

An atom of an element is denoted by a “symbol” Explain the meaning of the term ‘symbol’. State a reason for representing the following element by its symbol.

Copper by ‘Cu’

Match the metallic elements – with their correct symbols Metallic elements

Match the non-metallic elements – with their correct symbols. Non-metallic elements are:

Match the noble gases – with their correct symbols:

Give a reason why elements are tabulated in a table called the ‘Periodic table’.

Give the names and symbols of the first twenty elements of the periodic table.

Differentiate the first twenty elements of the periodic table into metals, non-metals, metalloids and noble gases.

Explain the term – molecules. Give three examples of atoms of the same element forming a molecule. State the atomicity of the same.

Give one example of a triatomic molecule

Give one example of a polyatomic molecule.

Explain the term compounds.

Give the example of a compound containing hydrogen and oxygen.

Give the example of a compound containing carbon and oxygen.

Give the example of a compound containing nitrogen and oxygen.

Give the example of a compound containing calcium and oxygen.

State two characteristics of water which prove that it is a – compound.

Explain the terms ‘chemical formula’.

State what a chemical formula denotes.

Give the symbol and the number of atoms of the following elements present in sodium chloride.

Give the symbol and the number of atoms of the following elements present in water.

Give the symbol and the number of atoms of the following elements present in carbon dioxide.

Give the symbol and the number of atoms of the following elements present in zinc chloride.

For writing a chemical formula – ‘symbols’ and combining capacity of an element with hydrogen i.e. ‘valency’ should be known. Explain the term – combining the capacity of an element i.e. valency.

State what are radicals. Give the names of the radicals –

(a) NO₃
(b) OH
(c) SO₄
(d) CO₃

Give the name of the radical - NO₃

Give the name of the radical - OH

Give the name of the radical - SO₄

Give the name of the radical - CO₃

Match the symbols of metallic elements – with their correct combining power or capacity.

(a) K
(b) Zn
(c) Al
(d) Na
(e) Ca
Combining power or capacity – A : 3 ; B : 2 ; C : 1. (positive valencies)

Match the symbols of non-metallic elements with their correct combining power or capacity.

(a) O
(b) S
(c) Cl

Combining power or capacity A : 3; B : 2; C : 1. (negative valencies)

Match the symbols of – radicals – with their correct combining power or capacity, (valency).

(a) OH
(b) So₄
(c) No₃
(d) Co₃

Combining power or capacity – A : 3; B : 2; C : 1. (negative valencies)

Write the formula of the compound formed – given symbols and combining power or capacity (valency) of the following element in the compound.

K¹⁺ Cl^1-

Write the formula of the compound formed – given symbols and combining power or capacity (valency) of the following element in the compound.

Na¹⁺ Cl^1-

Write the formula of the compound formed – given symbols and combining power or capacity (valency) of the following element in the compound.

Ca²⁺ NO₃^1-

Match the formulas of the following gases with their correct names :

Gases - (a) H₂ (b) N₂ (c) O₂ (d) Cl₂ (e) HCI (f) NH₃ (g) CO (h) CO₂ (i) SO₂ (j) NO (k) NO₂.

Names:

(1) Ammonia (2) Nitrogen Dioxide (3) Oxygen (4) Hydrogen (5) Nitrogen (6) Chlorine (7) Carbon Monoxide (8) Sulphur Dioxide (9) Nitrogen Monoxide (10) Carbon Dioxide (11) Hydrogen Chloride

Match the formulas of the following of acids with their correct names:
Acids – (a) HCI (b) HNO₃ (c) H₂SO₄ (d) H₂CO₃
Names – (1) Carbonic acid (2) Sulphuric acid (3) Hydrochloric acid (4) Nitric acid

Match the formulas of the following of bases with their correct names.

Bases – (a) NaOH (b) KOH (c) Ca(OH)₂ (d) Zn(OH)₂

Names – (1) Potassium hydroxide (2) Zinc hydroxide (3) Aluminium hydroxide (4) Calcium hydroxide (5) Sodium hydroxide

Complete the statement with the correct words.
Acid’s are chemicals which are _____ in taste and derived from plants and ________.

Complete the statement with the correct words.
_______  are chemicals which are hydroxide (or oxides) of  ______  eg. sodium hydroxide.

Complete the statement with the correct words.
__________ are chemicals formed on reaction of a base with an _____ giving salt and water.

In the chemical word equation – Zinc + Sulphuric acid → Zinc sulphate + Hydrogen

The molecular equation is :

Zn + H₂SO₄ → ZnSO₄ + H₂[g].

State what [g] represents.

In the chemical word equation –

Zinc + Sulphuric acid → Zinc sulphate + Hydrogen.

State the reactants and products of the above reaction. What does the arrow indicate?

Complete the statement given below by filling in the blank with the correct word.
An element is a pure substance which cannot be broken down by physical or _________ methods.

Complete the statement given below by filling in the blank with the correct word.

The basic unit of an element is an __________.

Complete the statement given below by filling in the blanks with the correct words.
Atom contains ________ , with positively charged _____.

Complete the statement given below by filling in the blank with the correct word.
Element ______ has the symbol derived from its Latin name ‘Argentum’

Complete the statement given below by filling in the blanks with the correct words.
From the elements – He, Br, Pt, and O; the element which is metallic is ____, an inert element is ____, forms a triatomic molecule is ____, is liquid at room temperature is_ ___.

Complete the statement given below by filling in the blank with the correct word.
From the elements nitrogen, chlorine, bromine, the element present in the atmosphere is ________.

Match the statements in List I – 1 to 10 correct answers in List II-A to J.

Select the correct answer from the choice given below.
The symbol of mercury is

Select the correct answer from the choice given below.

The type of element-phosphorus

Select the correct answer from the choice given below.
The type of molecule- bromine

Select the correct answer from the choice given below.
A compound

Select the correct answer from the choice given below.
The unreactive non-metallic element

Select the correct answer from the choice given below.
The negatively charged particles in an atom

Select the correct answer from the choice given below.
The element which is malleable

Select the correct answer from the choice given below.
An impure substance

Select the correct answer from the choice given below.
An element which is a poor conductor of heat

Select the correct answer from the choice given below.
A group of atoms of elements

Match the compounds in List I – 1 to 20 with their correct formulas from in List II-A to T.