Explanation:
For a non-spontaneous or non-
feasible process, ΔH>0 and ΔS<0. For a spontaneous or irreversible
reaction, ΔH<0 and ΔS>0. For an equilibrium or reversible process, ΔH=0 and ΔS=0.
Question 7
The hybridisation in NH
4
+
is
a) sp
b) sp
2
c) sp
3
d) sp
3
d
e) sp
3
d
2
Correct Answer:
c) sp
3
Explanation:
Number of valence electrons in N is 5 and in H it is 4.
So total number of valence electrons = 5 + 4 = 9; Charge = +1.
Therefore, total electrons in NH
4
+
= 9 - 1 = 8
When the total number of electrons is less than 8, divide by 2. If it lies between 9 and 56, divide it by
8.
8/2 = 4; X=4
Therefore, hybridisation in NH
4
+
is sp
3
.
Question 8
Slater's rule is used to calculate the value of
a) Screening constant
b) Electron affinity
c) Ionisation energy
d) Effective nuclear charge
e) Both a and d
Correct Answer:
e) Both a and d
Explanation:
The value of screening constant (S) and effective nuclear charge (Z
*
) can be calculated using Slater's
rule. Effective charge (Z
*
) = Z
– S (where Z- atomic number and S-screening constant).
Question 9
Which of the following solvents is suitable for S
N2
reactions?
a) Ethanol
b) Water
c) Acetonitrile
d) Acetic acid
e) t-butanol
Correct Answer:
c) Acetone
