Revision work for chemistry Grade-7 2021.

Revision work for chemistry Grade-7 2021. 

Chose the best.

1.    A hydrocarbon is a compound containing only hydrogen      and ----------------------.

A.   Sodium

B.   Carbon

C.   Chlorine

D.   All

2.       Fossil fuels are called --------------------------fuels.

A.      Renewable

B.      Non-renewable

C.      Both

D.      None of them

3.    In an oil refinery the --------------------- oil is separated into its fractions.

          A.      Olive

          B.      Seed

          C.      Crude

          D.      None of them

4.    Unsaturated compounds turn -----------------------------    bromine water     colourless.

         A.         Red

         B.         Blue

         C.         Black

         D.         Yellow

5.    The ------------------------------ have at least one double       bond between carbon atoms. 

A.    Alkanes

B.    Alkenes

C.    Alkynes

D.   All

True and False

1.    Most of our common fuels are fossil fuels. T

2.    Ethene and the other alkenes are called saturated   compounds. F

3.    When we burn a fuel, the reaction is called combustion. T

4.    Petrol is a mixture of hydrocarbons. T

5.    When hydrocarbons burn, they are reduced. F

6.    Carbon dioxide is given off from car exhausts. F

7.    Burning fossil fuels causes acid rain. T

8.    The Earth's atmosphere acts like a greenhouse. T

 Fill in the blanks.

1.    A hydrocarbon is a compound containing only hydrogen and -----------. carbon 

2.    Most of our common fuels are ---------------. fossil fuels 

3.    Fossil fuels are called --------------- fuels. non-renewable 

4.    In an oil refinery the crude oil is separated into                 its ------------------------. fractions

5.    Remember that a fraction is a group of hydrocarbons with similar ----------------------- points. boiling

6.    Cracking is when we break down large ----------------- into smaller, more useful ones. Hydrocarbons

7.    The -------------------- have at least one double bond between carbon atoms. Alkenes

8.    Ethene and the other alkenes are called --------------      compounds. Unsaturated

9.    Unsaturated compounds turn ---------------------- bromine water colorless. Yellow

10. When we burn a fuel, the reaction is called ---------------. combustion

11. Petrol is a  ----------------------- of hydrocarbons. Mixture

12. When hydrocarbons burn, they are -------------. 

oxidized

13. Carbon --------------------- is given off from car exhausts. Monoxide

14. Burning fossil fuels causes ---------------------. acid rain

15. Most petrol is -------------------free now. Sulfur

16. The Earth's atmosphere acts like a -----------------. greenhouse

17. plants absorb --------------------- gas. carbon dioxide


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