Showing posts with label Chemistry Form I. Show all posts
Showing posts with label Chemistry Form I. Show all posts

Test 02 Form one chemistry

 


Time: 80 min

Instructions:

Answer all questions

1)    For each of the following items, choose the most correct answer from the given alternatives and write its letter beside the number item.

i.        Which state of matter with particles closely packed together?

A.    Solid

B.    Liquid

C.    Gaseous

 

ii.        The process through which a solid substance changes directly into gas without passing liquid state is:

A.    Sublimation

B.    Deposition

C.    Evaporation

 

iii.        Which series of processes is correct for an ice to change into water vapour?

A.    Melting, boiling

B.    Melting, deposition

C.    Boiling, condensation

 

iv.        An element whose chemical symbol is the first two letters from its English name is:

A.    Magnesium

B.    Calcium

C.    Sodium

 

v.        Which statement is not true about a physical change?

A.    It is an irreversible change

B.    It is a reversible change

C.    It does not affect the composition of the substance

 

vi.        Among the following, which one is a chemical change?

A.    Water freezes to form an ice

B.    A chalk grinded into powder

C.    An iron sheet gets rust

 

vii.        Air composes _______ % by volume of nitrogen.

A.    78

B.    21

C.    3

 

viii.        Which method can be used to separate the mixture of water and floating solid particles?

A.    Decantation

B.    Filtration

C.    Fractional distillation

 

ix.        Which reason supports the statement “Water is a compound and not a mixture”?

A.    Formation of water involves chemical change

B.    Formation of water involves physical change

C.    Components of water may be seen separately

 

x.        The condition in which the lungs are not getting enough oxygen causing difficult in breathing is called:

A.    Suffocation

B.    Fainting

C.    Shock

 

2)    For each of the following statements write TRUE if the statement is correct and FALSE if the statement is incorrect.

       i.        Changes of states of matter is helpful in rainfall formation _________

      ii.        Sour of milk is the physical change of matter ______________

    iii.        Air is a homogeneous mixture that forms an alloy _______________

     iv.        Mercury is a liquid metal whose chemical symbol is Hg ________________

      v.        Water freezes to form water vapour __________

 

3)    (a) Define the following terms

                      i.        Matter

                    ii.        Boiling point

                   iii.        Melting point

                   iv.        Physical change

                     v.        Chemical change

 

(b) State any five (5) differences between physical and chemical change.

 

4)    (a) Changes of states of matter is very important in our daily life. State any five (5) importance of changes of states of matter.

(b) State whether each of the following changes is either physical or chemical change.

                      i.        Drying of a wet cloth

                    ii.        Melting of an ice

                   iii.        Grinded chalk

                   iv.        Evaporation of water

                     v.        Decaying of fish

 

5)    (a) Air is a homogeneous mixture of different gases in the atmosphere. Giving five (5) reasons, state why air is mixture and not a compound.

(b) A metal X was left exposed to air with moisture for two days. The metal was observed to have a reddish-brown colour on its surface.

                      i.        What is the name of element X?

                    ii.        Write a chemical formula of element X

                   iii.        What is the name of the colour observed on the metal surface?

                   iv.        Write any two methods that can be used to remove the colour observed on a metal surface.

 

Form one Chemistry Test





 Time: 50 min

Instructions:

Answer all questions

 

01. For each of the following items, choose the most correct answer from the given alternatives and write its letter beside the number item.

          i.            It is important to take note of the warning signs in the laboratory so as:

A.    To work safely in the laboratory

B.     We do not contaminate substances

C.     To work hard

 

       ii.            A person studying about medicine is known as a:

A.    A chemist

B.     A dentist

C.     A pharmacist

 

     iii.            The guess answers or solutions to a problem are in which step in six ways of solving scientific problem?

A.    Identification of problem

B.     Hypothesis formulation

C.     Experimentation

 

      iv.            Which one is true about the First Aid?

A.    It prevents illness

B.     It prevents further infections

C.     It promotes infections

 

        v.            The burns caused by hot liquids or vapour are:

A.    Scalds

B.     Vomiting

C.     Scurs

 

02. Write true if the statement is correct and false when the statement is incorrect.

a)      We are not allowed to test anything in the laboratory ____________________

b)      A scientist uses scientific procedure to solve a scientific problem ______________________

c)      Fertilizer is one of the products produced in agriculture and helps to kill weeds _____________________

d)      Vomiting is loss of consciousness _____________________

e)      Luminous flame is produced by a Bunsen burner when there is high supply of oxygen _____________________

 

03. (a) Define the following terms

i) Heat

ii) Flame

      (b) Give any four (4) differences between the two types of flame produced by a Bunsen burner.

 

04. (a) Define First aid, and give any four (4) reasons to why is it important.

(b) Write any four (4) rules of the laboratory, during practical work.

 

05.  (a) Explain six steps taken when solving a scientific problem.

(b) Explain any four (4) features of a good laboratory.

 

Answers: AIR, COMBUSTION, FIREFIGHTING AND RUSTING

01.  

i

ii

iii

iv

v

C

C

B

A

A

02.  

i)                 Combustion is the chemical reaction which involves the burning of a substance in the presence of oxygen

ii)               Combustible materials are the materials that catch fire and burn easily.

iii)              Flame is a zone of burning gas which produce heat and light.

iv)             Fire is the state or process of combustion in which ignited material combines with oxygen and gives off light, heat and flame.

v)              Firefighting is the extinguishing of harmful fires.

 

03.  Components required for the fire to burn are fuel, oxygen and heat.

04. (a)

i)                 Rust is the reddish-brown coating on the metal surface.

ii)               Rusting is a chemical process that occurs in iron or steel.

(b) Necessary conditions for rust to occur in iron or steel are moisture (water) and air (oxygen)

(c) Methods of preventing rusting

ü  Painting

ü  Oiling

ü  Galvanization

ü  Tin plating

ü  Use of silica gel

ü  Use of plastic

 


Answers: ELEMENTS, COMPOUNDS AND MIXTURES

01.  

i

ii

iii

iv

v

C

C

A

A

B

02.  

i)                 An element is a pure substance which cannot be split into simpler substances by any chemical means. Example Iron, silver, gold, Aluminium etc

ii)               A compound is a pure substance that is made up of two or more elements in chemical combination.

iii)              A mixture is a physical combination of two or more substances in any ratio.

iv)             A solvent is a component of the solution that dissolves other substances.

v)              A solute is the component in a solution that is dissolved in a solvent.

 

03. (a) Differences between mixture and compounds

Mixtures

Compounds

Compounds may be seen separately

Components cannot be seen separately

 

The components can be separated from one another by physical method

 

The constituent elements cannot be separated by physical means

Mixtures may vary widely in composition. The elements are mixed in any ratio

 

Compounds always have definite compositions by mass of the elements. The properties cannot be changed

 

No chemical change takes place when a mixture is formed

 

When new substances are formed, they involve a chemical change

 

The properties of a mixture are those of the individual elements

 

The properties of compounds are very different from those of individual elements

 

 

(b) Differences between suspensions and solutions

Solution

Suspension

It is homogeneous

It is heterogeneous

 

It is transparent or clear

It is opaque or not clear

 

Particles are completely dissolved

Particles separates on standing

 

Components are separated by evaporation

Components are separated by filtration

 

 

04. Uses of solvents

Solvents can be used:

ü  As the bleaching agent

ü  As stain removal

ü  As varnish removal

ü  As degreasing

ü  For cleaning

 

05.  

i)                 Immiscible liquids

ii)               Immiscible liquids

iii)              Miscible liquids

iv)             Immiscible liquids

v)              Miscible liquids

06.  

i)                 Sublimation

ii)               Layer separation (using separating funnel)

iii)              Fractional distillation

iv)             Magnetic

v)              Solvent extraction