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FBISE Chemistry XII (2018-First Group)

FBISE Chemistry XII (2018-First Group)

1. Br- reduces H2SO4 to form





... Answer is c)
Explanation:Br- is strong reducing agent and reduces H2SO4 to form SO2. In this reaction oxidation state of S decreases from +6 (in H2SO4) to +4 (in SO2).

2. Which of the following will not produce nitrite on heating?





... Answer is a)
Explanation: LiNO3 will not produce nitrite on heating like other alkali metals becuse lithium nitrite is unstable due to high polarizing power of Li+ ion and it docomposes to most stable lithium oxide.

3. In reaction with aqueous copper complex, [Cu(H2O)6]+2, NH3 acts as ligand well as





... Answer is b)
Explanation: Ammonia acts as base and produces [Cu(H2O)4(OH)2] when used in small amount while it acts as ligand and produces [Cu(NH3)4(H2O)2]+2 when used in excess amount.

4. Correct name of complex [Zn(NH2-CH2-CH2-NH2)3]+2 is





... Answer is c)
Explanation:Correct name of complex [Zn(NH2-CH2-CH2-NH2)3]+2 is Trisethylenediamine Zinc(II) ion

5. -SH is the functional group present in the organic compounds known as





... Answer is d)
Explanation: -SH is the functional group present in the organic compounds known as Thiols.

6. The electrophile in aromatic sulphonation reaction of benzen is





... Answer is c)
Explanation:The electrophile in aromatic sulphonation reaction of benzen is SO3 acts as an electrophile as it is an electron deficient.

7. Meta directing group among the following is





... Answer is c)
Explanation: Meta director has very little electron density at point of attachment with aromatic ring. -COOH is a meta directing group because its carbon is sp2 hybridized which withdraws electron density from benzene ring from ortho and para positions throgh inductive effect as well as through delocalization of pi electrons(resonance effect).

8. Which one of the following reducing agents reduces the aromatic nitro compounds to amines?





... Answer is a)
Explanation: Sn/HCl is used for reduction of aromatic nitro compounds to amines..

9. The alcohol with greater reactivity with respect to cleavage of its O-H bond is





... Answer is a)
Explanation: CH3OH is the most reactive with respect to cleavage of its O-H bond due formation of relatively stable methoxide ion.

10. Ethers can be prepared by reaction of alkyl halides with





... Answer is c)
Explanation: Ethers can be prepared by reaction of alkyl halides with Ag2O.

11. The reagent which is used to distinguish between aldehydes and alcohols is





... Answer is d)
Explanation: Aldehydes and ketones react with 2,4-dinitrophenylhydrazine to produce 2,4-dinitrophenylhydrazones in the presence of an acid. This reaction is also known as 2,4-DNP test and usd for the identification of aldehydes and ketones because 2,4-dinitrophenylhydrazones are usually yellow or orange crystalline solids.

12. Which of the following will not give idoform test on reaction with I2





... Answer is c)
Explanation: Iodofom test is given by those aldehydes or ketones which contain acetyl (CH3CO) group or secondary alcohols which contian methyl (CH3) group and OH group bonded with same carbon atom or ethanol. Hence, among above acetaldehydes and acetone contains acetyl groups, so both gives idoform test. However, among 1-propanol and 2-propanol, 2-propanol constains methyl group and OH bonded with same carbon atom and can give idoform test while, 1-propanol can not give iodoform test.

13. Reduction of carboxylic acid with LiAlH4 results in the formation of





... Answer is a)
Explanation: Reduction of carboxylic acid with LiAlH4 results in the formation of primary alcohol. As carboxylic acids are less reactive than aldehydes and ketones, so these can be reduced only by LiAlH4.

14. Which one of the following is not a disaccharide





... Answer is c)
Explanation: Glactose (C6H12O6) is a monosacharide.

15. Nail Polish remover is composed of





... Answer is c)
Explanation: Nail polish remover is composed of ethyle acetate and aceton.

16. Industrial smog contains smoke mixed with





... Answer is b)
Explanation: Industrial smog contains smoke and SO2 from burning of fossil fuels.

17. The technique which is used to determine the position of carbon atoms in organic compound is





... Answer is c)
Explanation: NMR spectroscopy useful in in deternining the number and types of proton in a moleucle. It is also useful in determining the position of carbon atom. Chemistry FBISE Chemistry Group second 2018

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