Revision work for chemistry Grade-8 First term 2021.


Revision work for chemistry Grade-8 

First term 2021. 

Chose the best.

What type of reactions can able to change products back to the their original form?

Reversible reactions Irreversible reactions

What is meant by the term Hydration in Chemistry?

removing water from a substance adding water to a substance adding oxygen to a substance adding Hydrogen to a substance

What is meant by the term Dehydration in Chemistry?

adding Water to a substance removing water from a substance adding oxygen to a substance adding Nitrogen to a substance

Which is the correct symbol to show a reversible reaction?

=   >

What is the color and shape of Hydrated Copper Sulfate ?

White powder blue powder blue crystals white crystals

What is the color and structure of anhydrous copper sulfate?

white powder black crystlas blue crystals red powder

Dehydration is a ................................... process .

endothermic exothermic

What term is used to describe a chemical reaction in which the forwards and reverse rates are equal, so the amount of product remains constant?

Static equilibrium Dynamic equilibrium 

What happens if you remove some of one of the products from a system at dynamic equilibrium?

Less products are made More products are made More reactants are made

What is the effect of increasing the pressure on the following reaction: 2NO + O2  2NO2?

The yield of NO2 increases The yield of NO2 decreases The reaction is slower


True and False

    

Changes which can go backwards or forwards are called reversible. T

 

2.    The energy absorbed in the forward reaction is the same as the energy given out in the reverse reaction. T

3.    At equilibrium, the rate of the forward reaction and the reverse reaction is the same. T

4.    Dynamic' refers to movement.T

5.    When equilibrium is reached, the amount of each substance stays the same. T

 

6.    The position of equilibrium shifts to try to cancel out any changes you introduce.T

 

7.    We can define a base as a proton acceptor.T

8.    For a strong acid plus a weak alkali, use methyl orange indicator.T

 

9.    For a weak acid and a strong alkali, use phenolphthalein indicator.T

 

 

10. Two non-metal atoms can both gain Protons by sharing. F

 

11. Shared electrons form covalent bonds between metal atoms.F

 

12. Carbon has 2 electrons in its outer shell. F

 

13. The lst shell is filled by just 8 electrons. F

 

14. Carbon dioxide is another molecule which contains a double bond. T

 

 

15. Substances with giant covalent structures are not soluble in water.T

16. Diamond and graphite are allotropes of carbon. T

 

17. Substances, with low melting points and boiling points have simple molecular structures. T

 

18. In general the larger the molecule, the stronger the intermolecular forces.T

 Fill in the blanks.

1.    Diamond is made from only ------------------- atoms. carbon

 

2.    Both carbon and hydrogen atoms need to gain ---------------------. electrons

3.    We can define an -------------------- as a proton donor. Acid

4.     Hydration is a ----------------------- process. exothermic

5.     In a reversible reaction, if forward reaction is exothermic .Then backward reaction will be------------------. Endothermic


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