Which one of the following order is correct for the first ionisation energies of the elements?
B <Be <N < O
Be <B <N < O
B <Be <O <N
B <O <Be <N
C.
B <Be <O <N
D.
B <O <Be <N
First ionisation energy increases in a period. Thus, the first IE of the elements of the second period should be as follows
Be <B <N <O
But in practice, the elements do not follow the above order. The first IE of these elements is
B <Be <O < N
The lower IE of B than that of Be is because in B (1s2, 2s2,2p1), electron is to be removed from 2p which is easy while in Be (1s2, 2s2), electron is to be removed from 2s which is difficult. The low IE of O than that of N is because of the half-filled 2p orbitals in N (1s2, 2s2,2p3).
The cubic unit cell of a metal (molar mass = 63.55 g mol-1) has an edge length of 362 pm. Its density is 8. 92 g cm-3. The type of unit cell is
primitive
face centred
body centred
end centred
The equilibrium constant for the given reaction is 100.
What is the equilibrium constant for the reaction given below?
10
1
0.1
0.01
20 mL of 0.1 M acetic acid is mixed with 50 mL of potassium acetate. Ka of acetic acid = 1.8 x 10-5 at 27C. Calculate concentration of potassium acetate if pH of the mixture is 4.8.
0.1 M
0.04 M
0.4 M
0.02 M
Match the following.
List I | List II | ||
(A) | Flespar | (I) | [Ag3SbS3] |
(B) | Asbestos | (II) | Al2O3.H2O |
(C) | Pyrargyrite | (III) | MgSO4.H2O |
(D) | Diaspore | (IV) | KAlSi3O8 |
(V) | CaMg3(SiO3)4 |
(A) (B) (C) (D)
IV V II I
(A) (B) (C) (D)
IV V I II
(A) (B) (C) (D)
IV I III II
(A) (B) (C) (D)
II V IV I
The concentration of an organic compound in chloroform is 6.15 g per 100 mL of solution. A portion of this solution in a 5 cm polarimeter tube causes an observed rotation of -1.2°. What is the specific rotation of the compound?
+12
-3.9
-39
+61.5
Fluorine reacts with dilute NaOH and forms a gaseous. product A. The bond angle in the molecule of A is
104°40'
103°
107°
109°28'