PLZ HELP ME IN THESE CHEM. QUESTIONS

[sweetie]

Q.39
Q.35
Q.27
Q.24
Q.22
Q.21

[Sue T]

Q21) this molecule has an alkene group (th double bond) so the mno4- will oxidise it
 you start by adding an OH group on each side of the double bond. u end up wth:
HOCH2CH2CH2 CH(OH)CH2CHOH        notice tht u keep th hydroxy group tht ws already ther is kept.

c wer th double bond was? (i left a little gap) since th mno4- is hot & conc, the molecule will get oxidised further - it will split in2 2fragments @ th place were th double bond was

so the first fragment HOCH2CH2CH2 th carbon tht had th double bond is attached 2 only 1 other carbon so a carboxylic acid is formed (is that carbon ws attached to 2 other, a ketone would form)
CH3CH2COOH (with th same no. of carbons)

the second fragment has 2 OH groups n th previously double-bonded- carbon is attached 2 only one other carbon therefore we'll have 2 carboxylic acid groups.

thts it! hope u get it (its pretty confusing)

[sweetie]

 i kinda understud, but why is option "D" wrong ?

 cud u also xplain Q's -- 39 and 24!!!
Thank You

[tmisterr]

q21. d is wrong because the hydroxy propanoic acid contains a primary alcohol group which will be oxidised to a carboxylic acid in the presence of hot concentrated manganate (VII) ions

q39. during free radical substitution of propane there will be two propyl free radical which will join to form a hexane, C₆H₁₄ and or its structural isomer. 1, and 2 are possible but 3 has 15 hydrogen atoms therefore it is not an isomer of hexane and cannot be formed.

q24. the first reaction is slow, think of why? High activation energy. high activation energy means there are less molecules who have this energy or more. less molecules taking part in reaction equals a slower rate of reaction. second reaction is faster so it has a lower activation energy than the first reaction. since there is two reactions in the mechanism, you will automatically rule out A and D which two one and two reactions respectively. Answer is C because the first reaction should have a higher activation energy than the second one.