Correct Answer:
b) Si-Ge
Explanation:
Si-Ge is a semi conductor. Its conductivity is due to the presence of impurities in the compound. NaCl
is a conductor. Nb3Ge is a super conductor. Sulphur compound is used as rubber products, so it is an
insulator. SiO2 is sand and is also an insulator.
Question 4
Which of the following binary systems is completely miscible on raising the temperature?
a)
Phenol-H2O
b)
Aniline-Hexane
c)
H2O-Aniline
d)
Carbon disulphide-Methyl alcohol
e)
All of these
Correct Answer:
e) All of these
Explanation:
All the above binary mixtures are completely miscible on raising the temperature. The consolute
temperature for Phenol-H2O is 68.10C, for Aniline-Hexane it is 59.60C, for H2O-Aniline it is 1670C,
for Carbon disulphide-Methyl alcohol it is 40.50C. The consolute temperature is the critical
temperature below or above which a mixture is completely miscible.
Question 5
The oxidation number of a Group VIIA element in a compound is
a)
+1
b)
-1
c)
0
d)
+2
e)
Depends upon the element combined with an electronegative atom
Correct Answer:
e) Depends upon the element combined with an electronegative atom
Explanation:
The oxidation number of a Group VIIA element in a compound is -1, except when that element is
combined with one having higher electronegativity. For example, oxidation number of Cl in HCl is -1,
but the oxidation number of Cl in HOCl is +1.