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Published on: 20/10/2025
Download Tamil Nadu 12th Standard Chemistry question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
Questions + Answers key
Take MCQ Chemistry Test
1.
The oxidation state of 'P' in H3PO4 is ______.
+2
+5
+6
+7
2.
The molecular formula of hypo phosphorous acid is ______.
H2P2O4
H2P2O6
H3PO2
H3PO3
3.
Phosphorus trichloride is used as a ______.
phosphating agent
oxidising agent
chlorinating agent
reducing agent
4.
The scarlet and violet amorphous state are also known for ______.
Ca
Sc
Cr
P
5.
Phosphorus has layer structure and it acts as a ______.
conductor
semiconductor
insulator
none
6.
The ________ phosphorus can be converted to __________ phosphorus by heating it to 420oC in the absence of air and light.
white to red
red to white
blue to red
red
7.
It has a characteristic garlic smell ______.
N
O
H
P
8.
The structure of N2O3 is ______.
9.
Which one is a blue solid?
N2O5
H2CO3
N2O3
NO2
10.
Which one is a brown gas?
NO2
NO3
N2O5
H2O2
11.
Which one is used in gun powder for fire arms?
NaNO2
NaOH
NaNO3
NH4OH
12.
The oxidation state of N in HNO3 is ______.
+3
+5
+2
+1
13.
Nitration takes place due to the formation of __________ ion.
nitrosonium
nitronium
hydrogen
both (a) & (b)
14.
HNO3 act as a/an __________ agent.
oxidising
nitrating
both (a) & (b)
none
15.
NH3 is molecule is ______ in structure.
octahedral
tetrahedral
planar
linear
16.
NH3 is molecule is ______ in shape.
pyramidal
octahedral
tetrahedral
square planar
17.
When excess ammonia is added to aqueous solution of CuSO4 a _________ colour compound [Cu(NH3)4]2+ is formed.
deep red
dark violet
dark green
deep blue
18.
Ammonia reacts with metallic salts to give ______.
metal hydrides (in case of Mg)
metal hydroxides (in case of Fe)
metal oxides
none
19.
NH3 is a _______ agent.
oxidising
inert
reducing
both (a) & (c)
20.
2NH3 \(\frac{?}{\Delta}\) N2 + 3H2
>540oC
>500oC
<500oC
<540oC
21.
NH3 is good ionizing solvent like ______.
H2O
OH
CHO
None of these
22.
In NH3, at low temperatures two soluble hydrate __________ & _________ are isolated.
NH4.H2S
NH3.H2O & H2O2
NH3.H2O & 2NH3.H2O
NH3.5H2O & NH3.2H2O
23.
NH3 is a ________ smelling gas.
odourless
pungent
garlic odour
both (b) & (c)
24.
In Haber process ________ acts as catalyst.
Fe
P2O5
H2SO4
HNO3
25.
Which one is chemically inert?
N2
F
CI
None of these
26.
Nitrogen, the principal gas of atmosphere is separated industrially from liquid air by ______.
distillation under reduced pressure
crystallisation
distillation
fractional distillation
27.
Which one is a solid in Nitrogen family?
P
As
Bi & Sb
All of these
28.
The basicity of hypophosphorous acid is ______.
1
2
3
4
29.
Strong reducing behaviour of H3PO2 is due to______.
High oxidation state of phosphorus
High electro gain enthalpy of phosphorus
Presence of two-OH groups and one P-H bond
Presence of one-OH groups and two P-H bonds
30.
Which of the following halides of group 15 is not hydrolysed?
NF3
PF3
NI3
Both (a) and (b)
31.
Catenation property of group 15 elements, follow the order _______.
N < P < As < Sb < Bi
P >> N > As > Sb > Bi
P < N < As < Sb < Bi
N>> P > As > Sb > Bi
32.
Which of the following is correct?
H3PO3 is dibasic and reducing
H3PO3 is dibasic and non-reducing
H3PO4 is tribasic and reducing
H3PO3 is tribasic and non-reducing
33.
The molarity of given orthophosphoric acid solution is 2M. Its normality is _______.
6N
4N
2N
none of these
34.
The basicity of pyrophosphorous acid ( H4P2O5) is _______.
4
2
3
5
35.
P4O6 reacts with cold water to give _______.
H3PO3
H4P2O7
HPO3
H3PO4
36.
On hydrolysis, PCl3 gives________.
H3PO3
PH3
H3PO4
POCl3
37.
Solid (A) reacts with strong aqueous NaOH liberating a foul smelling gas(B) which spontaneously burn in air giving smoky rings. A and B are respectively_________.
P4(red) & PH3
P4(white) & PH3
S8 & H2S
P4(white) & H2S
38.
An element belongs to group 15 and 3rd period of the periodic table, its electronic configuration would be_______.
1s2 2s2 2p4
1s2 2s2 2p3
1s2 2s2 2p6 3s2 3p2
1s2 2s2 2p6 3s2 3p3
39.
Which is true regarding nitrogen?
least electronegative element
has low ionisation enthalpy than oxygen
d- orbitals available
ability to form pπ-pπ bonds with itself
40.
In which of the following, NH3 is not used?
Nessler's reagent
Reagent for the analysis of IV group basic radical
Reagent for the analysis of III group basic radical
Tollen's reagent
1.
(b)
+5
2.
(c)
H3PO2
3.
(c)
chlorinating agent
4.
(d)
P
5.
(b)
semiconductor
6.
(a)
white to red
7.
(d)
P
8.
(c)
9.
(c)
N2O3
10.
(a)
NO2
11.
(c)
NaNO3
12.
(b)
+5
13.
(b)
nitronium
14.
(c)
both (a) & (b)
15.
(b)
tetrahedral
16.
(a)
pyramidal
17.
(d)
deep blue
18.
(b)
metal hydroxides (in case of Fe)
19.
(c)
reducing
20.
(b)
>500oC
21.
(a)
H2O
22.
(c)
NH3.H2O & 2NH3.H2O
23.
(b)
pungent
24.
(a)
Fe
25.
(a)
N2
26.
(d)
fractional distillation
27.
(d)
All of these
28.
(a)
1
29.
(d)
Presence of one-OH groups and two P-H bonds
30.
(d)
Both (a) and (b)
31.
(b)
P >> N > As > Sb > Bi
32.
(a)
H3PO3 is dibasic and reducing
33.
(a)
6N
34.
(b)
2
35.
(a)
H3PO3
36.
(a)
H3PO3
37.
(b)
P4(white) & PH3
38.
(d)
1s2 2s2 2p6 3s2 3p3
39.
(d)
ability to form pπ-pπ bonds with itself
40.
(a)
Nessler's reagent
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