321. Which of the following is not correct about xenon hexafluoride?
A
It has oxidation state of + 6.
B
The hybridisation involved in $$Xe{F_6}$$ is $$s{p^3}{d^3}.$$
C
The shape of $$Xe{F_6}$$ is distorted octahedral and can be represented as 
D
On hydrolysis it gives $$Xe, HF$$ and $${O_2}.$$
Answer :
On hydrolysis it gives $$Xe, HF$$ and $${O_2}.$$
322. The bond dissociation energy of $$B - F$$ in $$B{F_3}$$ is $$646\,kJ\,mo{l^{ - 1}}$$ whereas that of $$C - F$$ in $$C{F_4}$$ is $$515\,kJ\,mo{l^{ - 1}}.$$ The correct reason for higher$$B-F$$ bond dissociation energy as compared to that of $$C - F$$ bond is
A
stronger $$\sigma $$ bond between $$B$$ and $$F$$ in $$B{F_3}$$ as compared to that between $$C$$ and $$F$$ in $$C{F_4}$$
B
significant $$p\pi - p\pi $$ interaction between $$B$$ and $$F$$ in $$B{F_3}$$ whereas there is no possibility of such interaction between $$C$$ and $$F$$ in $$C{F_4}$$
C
lower degree of $$p\pi - p\pi $$ interaction between $$B$$ and $$F$$ in $$B{F_3}$$ than that between $$C$$ and $$F$$ in $$C{F_4}$$
D
smaller size of $$B$$ - atom as compared to that of $$C$$ - atom.
Answer :
significant $$p\pi - p\pi $$ interaction between $$B$$ and $$F$$ in $$B{F_3}$$ whereas there is no possibility of such interaction between $$C$$ and $$F$$ in $$C{F_4}$$
323. Among the following the electron deficient compound is
A
$$BC{l_3}$$
B
$$CC{l_4}$$
C
$$PC{l_5}$$
D
$$BeC{l_2}$$
Answer :
$$BC{l_3}$$
boron contains six electrons in its valence shell so, it is capable to accommodate one pair of electrons. Hence, it acts as Lewis acid or electron deficient ( incomplete octate ) compound. As we know that Lewis acids are
the substances having a tendency to accept a pair of electron. 324. A one litre flask is full of brown bromine vapours. The intensity of brown colour of vapours will not decrease appreciably on adding to the flask some
A
pieces of marble
B
animal charcoal powder
C
carbon tetrachloride
D
carbon disulphide
Answer :
pieces of marble
325. $$C{O_2}$$ is not a poisonous gas but there is increase in concentration of $$C{O_2}$$ in the atmosphere due to burning of fossil fuels and decomposition of limestone. The increase in concentration of $$C{O_2}$$ may lead to
A
increase in photosynthesis in plants
B
higher concentration of $$C{O_2}$$ in water
C
increase in greenhouse effect, thus raising the temperature
D
increase in formation of metal carbonates
Answer :
increase in greenhouse effect, thus raising the temperature
326.
Which of the following is correct about the reaction ?
\[3NaClO\xrightarrow{\text{heat}}NaCl{{O}_{3}}+2NaCl\]
A
It is disproportionation reaction
B
Oxidation number of $$Cl$$ decreases as well as increases in this reaction
C
This reaction is used for the manufacture of halates
D
All of these
Answer :
All of these
327. Which one of the following statements about the zeolites is false?
A
They are used as cation exchangers
B
They have open structure which enables them to take up small molecules
C
Zeolites are aluminosilicates having three dimensional network
D
Some of the $$SiO_4^{4 - }$$ units are replaced by $$AlO_4^{5 - }$$ and $$AlO_6^{9 - }$$ ions in zeolites
Answer :
Some of the $$SiO_4^{4 - }$$ units are replaced by $$AlO_4^{5 - }$$ and $$AlO_6^{9 - }$$ ions in zeolites
328. Which of the following is not true about structure of carbon dioxide?
A
In $$C{O_2},$$ carbon is $$sp$$ - hybridised.
B
$$C$$ forms two sigma bonds one with each oxygen atom and two $$p\pi - p\pi $$ bonds.
C
$$C{O_2}$$ is a linear covalent compound.
D
It is a polar molecule.
Answer :
It is a polar molecule.
329. Which of the following compounds is formed in borax bead test?
A
Metaborate
B
Tetraborate
C
Triborate
D
Orthoborate
Answer :
Metaborate
330. The element of group 17 whose half life is in milliseconds only is
A
$$Ts$$
B
$$Te$$
C
$$At$$
D
$$Og$$
Answer :
$$Ts$$