12th Chemistry Revision Exam Question - Answers
12TH STANDARD CHEMISTRY
TIME: 3HRS MARKS:
70
PART-I
CHOOSE THE CORRECT ANSWER: 15
× 1
= 15
1. 𝑆𝑐(𝑍 = 21) is a transition element but 𝑍𝑛(𝑍 = 30) is not
because,
a) Both 𝑆𝑐3+ and 𝑍𝑛2+ ions are colourless
and form white compounds.
b)
In case of 𝑆𝑐, 3𝑑- orbital are partially filled but in 𝑍𝑛 these are
completely filled.
c) Last electron
as assumed to be added
to 4𝑠 level in case of 𝑍𝑛
d)
Both 𝑆𝑐 and 𝑍𝑛 do not exhibit
variable oxidation states
Answer: b) In case of 𝑆𝑐, 3𝑑- orbital are partially filled but in 𝑍𝑛 these are completely filled.
2. The stability of +1 oxidation state
increases in the sequence,
a) 𝐴𝑙 < 𝐺𝑎 < 𝐼𝑛 < 𝑇𝑙 b) 𝑇𝑙 < 𝐼𝑛 < 𝐺𝑎 < 𝐴𝑙
c) 𝐼𝑛 < 𝑇𝑙 < 𝐺𝑎 < 𝐴𝑙 d) 𝐺𝑎 < 𝐼𝑛 < 𝐴𝑙 < 𝑇𝑙
Answer:a) 𝐴𝑙 < 𝐺𝑎 < 𝐼𝑛 < 𝑇𝑙
3. Solid 𝐶𝑜2 is an example of,
a) Covalent solid b)
Metallic solid c) Molecular solid d) Ionic
solid
4. Match items in
column-I with the items of column-II and assign the correct code. Column-I Column-II
A) Cyanide process (i) Ultrapure Ge
B) Froth floatation process (ii)
Extraction of Al
C) Electrolytic reduction (iii) Dressing
of ZnS
D) Zone refining (iv)
Extraction of Au code A B C D
a)
i ii iii iv
b)
iii iv ii i
c)
iv iii ii i
d)
ii iii i iv
5. 𝛼 − 𝐷(+) glucose and 𝛽 − 𝐷(+) glucose are,
a) Epimers b) Anomers c) Enantiomers d) Conformational isomers
6. The product formed, when glycol treated
with conc 𝐻2𝑆𝑜4 is,
a) 1,4 –dioxane b)
1,2 –epoxy ethane c) Ethene d) Ethanal
7. Which of these is
not likely to act as Lewis base?
a) 𝐵𝐹3 b) 𝑃𝐹3 c) 𝐶𝑂 d) 𝐹−
8. The 𝑃𝐻 of 10−5 𝑀 𝐾𝑂𝐻 solution will be,
a) 9 b) 5 c) 19 d) 14
9. Which one of the
following is the strongest acid?
a) 2-nitrophenol b) 4-chlorophenol c) 4-nitrophenol d) 3-nitrophenol
10. Williamson synthesis of preparing dimethyl ether is a/an,
a) 𝑆𝑁1 reaction b) 𝑆𝑁2 reaction
c) electrophilic addition d) electrophilic substitution
11. Acid hydrolysis of inulin produces,
a) Fructose b) Glucose c) Maltose d) Sucrose
12. In Froth floatation process, sodium cyanide
act as,
a) Frothing agent b) Collector c) Depressing agent d) Flux
13. Which of the
following metals has the largest
abundance in the earth’s crust?
a) Aluminium b)
Calcium c) Magnesium d)
Sodium
14. Assertion: 𝐶𝑒4+ is used as an oxidizing agent in volumetric
analysis
Reason: 𝐶𝑒4+ has the tendency
of attaining +3 oxidation state
a) Both assertion and reason are true and reason is the correct
explanation of assertion
b) Both assertion and reason are true but reason is not the correct explanation of assertion
c)
Assertion is true but reason
is false
d)
Both assertion and reason are false
15. The number
of carbon atoms per unit cell
of diamond is,
a) 8 b) 5 c) 1 d) 4