Which of the following is a Lewis acid ?
OH-
H+
F-
NH3
B.
H+
Lewis acid is any substance that can accept a pair of non- bonding electrons, such as the H+ ions. It is an electron pair acceptor.
Lewis base is any substance that can donate a pair of electrons.
OH-, F- and NH3 are Lewis base because they can donate a lone pair of electrons while H+ is a Lewis acid because it can accept a lone pair of electrons.
What is the H of the reaction?
CH2Cl2 (g) C (g) + 2H (g) + 2Cl (g)
The average bond energies of C-Cl bond and C-H bond are 416 kJ and 325 kJ mol-1 respectively.
1482 kJ
1482 J
1492 kJ
1492 J
A.
1482 kJ
In the reaction, two moles of C-H bonds and two moles of C-Cl bonds are broken. Hence, energy absorbed is
= 2 x 416 + 2 x 325
= 1482kJ
CaC2 and H2O react to produce
CH4
C2H4
C2H2
C2H6
C.
C2H2
CaC2 and H2O reacts to produce C2H2 (acetylene gas).
CaC2(s) + 2H2O(l) Ca(OH)2(aq) + C2H2
The only o p-directing group which is deactivating in nature is
-NH2
-OH
-X(halogens)
-R(alkyl groupd)
D.
-R(alkyl groupd)
-NH2, -OH and -R (alkyl groups) all are o/p- directing and they activates the benzene ring -(X) halogens are however o/p-directing but deactivate the benzene ring by withdrawing electrons fron the ring due to -I effect.
Which of the organic compounds will give red colour in Lassaigne test ?
C6H5NH2
None of these
B.
If both nitrogen and sulphur are present in a organic compound, they will give red blood colour with Lassaigne test due to the formation of ferric thiocyanate.
Na + C + S + N NaSCN (sodium thiocyanate)
Fe3+ + 3NaSCN Fe(SCN)3 + 3Na+
ferric thiocyanate
Which of the following is a wrong statement ? In a given period of the Periodic Table, the s-block element has, in general, a higher value of
electronegativity
atomic radius
ionisation energy
electron affinity
B.
atomic radius
Electronegativity, ionisation energy and electron affinity of s-block elements in their respective period is low but the atomic radius of the s-block elements is larger in their respective period due to less effective nuclear charge.
Inorganic benzene is
B3N6H3
B3N3H6
Al3N3H6
None of these
B.
B3N3H6
B3N3H6 (borazine) is known as inorganic benzene. Borazine is isoelectronic, i.e. same number of electrons and isosteric, i.e. same number of atoms with benzene.
Ammonia gas can be dried over
CaCl2
conc. H2SO4
P2O5
quick lime
D.
quick lime
Ammonia is dried over quick lime (CaO). It cannot be dried over conc. H2SO4, P2O5 and CaCl2 because it reacts with these compounds.
The IUPAC name of the following compound is
1, 2-dimethyl-2-butenol
3-methylpent-3-en-2-ol
3, 4-dimethyl-2-buten-4-ol
None of the above
B.
3-methylpent-3-en-2-ol
IUPAC name of the above compound is 3-methylpent-3-en-2-ol
The bond length of HCl bond is 2.29 x 10-10 m. The percentage ionic character of HCl, if measured dipole moment is 6.226 x 10-30 C- m, is
8%
20%
17%
50%
C.
17%
= e x d = 1.6 x 10-19 x 2.29 x 10-10
= 3.664 x 10-29 C-m
% ionic character =
= 17%