1ANS 1 OPTION B
2 D
3B
4D
LAST 2 ARE GUESSES
Q1 Which hydride ha no reaction with water
a)NH3
b)CH4
c)PH3
d)NaH
Q2 which one is highly flammable in nature
a)NaBH4
b)LiAlH4
c)B2H6
d)CH4
Q3 which undergoes spontaneous combustion with exposure to air
a)PH3
b)P2H4
c)N2H4
d)NH3
Q4 which undergoes detonation when stuck
a)P2H4
b)NH3
c)N2H4
d)N3H
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14 Answers
106Q1. NH3 reacts with water to form NH4+ same with PH4. NaH reacts with water to form NaOH while methane ka kabhi paani ke saath react karte dekha hai kya?? [3]
24ya ans is CH4....but bigger ques is why CH4 doesnt react with water ?
106how will it react and to form what ??
see. C-H bond strength is very high so it cant be cleaved.. (heterolytically or homolytically that is why methyl carbocation and free radicals are unstable)
further it has no d-orbitals for hydrolysis ... so neither can C-H bond be cleaved nor can hydrolysis take place.. hence no reaction
1ya, rightly said asish.
Q.2) its surely a) NaBH4 , as its given flammable by nature.
NaBH4 is flammable in its solid state but stable in solutions. in solution state only, its used as reducing agent in organic reactions. LiAlH4 is not flammable by nature, but its more reactive in solution state than NaBH4. thats why NaBH4 reduces only aldehydes and ketones to alcohols, while Li[AlH4] reduces a variety of products.
B2H6 and CH4 are stable hydrides bye their structure and bond strengths.
Q.3) NH3 and PH3 are stable in air in their pure form. , but catch fire at high temperatures.
N2H4 is highly reactive in air.
N2H4 + O2 → N2 + 2H2O.
This reaction takes place readily as two very stable products are formed.
P2H4 is even more reactive than N2H4, giving a similar reaction, but forming P4 , rather than P2. ( P2 is unstable becoz of weak p-pi - p-pi overlap )
if its a single answer question, it should be P2H4
Q.4) What i hv read in practical chemistry, detonation is bit similar to deflggeration.
NH3 is a stable gas , while its dimer is stable too. similar case for P2H4.
So, it should be d - HN3 as its a covalent azide.
( normally ionic azides are stable while covalent azides are not.)
1then, whats the answer of 2). If its not a) , then b) fr sure. but , then question should specify in which state ? ( solution or solid ?)
11Ans 2) Yeah it should be (c)
Diborane is a colorless, flammable, toxic gas, with a sickly sweet odor. It is highly reactive. It catches fire spontaneously in air and explodes with dioxygen. The heat of combustion is very high.
B2 H6 + 3O2 → 2 B2O3 + 3H2O ......Heat of combustion = -2165 KJ/ mol -1