Following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Q.1. Assertion(A) : Carbon is the only element that can form large number of compounds.
Reason (R) : Carbon is tetravalent and shows the property of catenation.
Answer
(d)Q.2. Assertion(A) : If the first member of a homologous series is methanal, its third member will be propanal.
Reason (R) : All the members of a homologous series show similar chemical properties.
Answer
(b)Q.3. Assertion(A) : Diamond and graphite are allotropes of carbon.
Reason (R) : Some elements can have several different structural forms while in the same physical state. These forms are called allotropes.
Answer
(a)Q.4. Assertion(A) : Soaps are not suitable for washing purpose when water is hard.
Reason (R) : Soaps have relatively weak cleansing action.
Answer
(b)Q.5. Assertion(A) : Carbon compounds can form chain, branched and ring structures.
Reason (R) : Carbon exhibits the property of catenation.
Answer
(a)Q.6. Assertion (A) : Carbon monoxide is extremely poisonous in nature.
Reason (R) : Carbon monoxide is formed by complete combustion of carbon.
Answer
(c)Q.7. Assertion (A) : Cooking oil decolourises bromine water.
Reason (R) : Cooking oil is a saturated compound.
Answer
(b)Q.8. Assertion (A) : In a candle, wax vapours burn in sufficient supply of oxygen, which leads to blue flame.
Reason (R) : When the oxygen supply is sufficient, then fuels burn completely producing a blue flame.
Answer
(a)Q.9. Assertion (A) : Alkanes give addition reaction.
Reason (R) : Addition reactions are a characteristic property of unsaturated hydrocarbons.
Answer
(d)Q.10. Assertion(A): n-butane and iso-butane are examples of isomers.
Reason (R) : Isomerism is possible only with hydrocarbons having 4 or more carbon atoms.
Answer
(b) Q.11. Assertion(A): Saturated hydrocarbons are chemically less reactive.
Reason (R) : All the valencies of carbon atom are satisfied by single covalent bonds.
Answer
Ans. (a) Q.12. Assertion(A): Diamond and graphite do not have the same crystal structure.
Reason (R) : Diamond is crystalline while graphite is amorphous.
Answer
Ans. (c) Q.13. Assertion(A): Graphite is soft and slippery to touch.
Reason (R) : Graphite has sheet like layered structure.
Answer
Ans. (a) Q.14. Assertion(A): Both aldehydes and ketones contain carbonyl group.
Reason (R) : In aldehydes, the functional group is attached to atleast one hydrogen atom.
Answer
Ans. (b) Q.15. Assertion(A): In alkanes, alkenes and alkynes the valency of carbon is always four.
Reason (R) : All hydrocarbons except alkanes contain double bonds.
Answer
Ans. (c) Q.16. Assertion(A): Graphite is a good conductor of electricity.
Reason (R) : It has one free valence electron.
Answer
Ans. (a) Q.17. Assertion(A): The functional group present in alcohols is – OH.
Reason (R) : It is the same group as present in water, hence water and alcohol have similar properties.
Answer
Ans. (c) Q.18. Assertion(A): Ethanol is first member of the alcohol homologous series.
Reason (R) : A homologous series can be represented by a general formula.
Answer
Ans. (d)Q.19. Assertion(A): Carbon and its compounds can be used as fuels.
Reason (R) : They are highly inflammable and have high calorific value.
Answer
Ans. (a)Q.20. Assertion(A): Covalent compounds are generally poor conductor of electricity.
Reason (R) : They consist of molecules and not ions which can transfer charge.
Answer
Ans. (a)Q.21. Assertion(A): Diamond is not good conductor of electricity.
Reason: It has no free electrons.
Answer
Ans. (a) Q.22. Assertion(A): Olefins have the general formula CnH2n+1
Reason (R) : There is at least one double bond between two carbon atoms in their molecules.
Answer
Ans. (d) Q.23. Assertion(A): Carbon possesses property of catenation.
Reason (R) : Carbon atoms form double as well as triple bonds during catenation.
Answer
Ans. (b) Q.24. Assertion(A): Two members of a homologous series have similar chemical properties.
Reason (R) : Propane and butane are members of same homologous series.
Answer
Ans. (b) Q.25. Assertion(A): Diamond is the hardest natural known substance.
Reason (R) : Diamond is used for cutting marble, granite and glass.
Answer
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