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12th Standard Chemistry English Medium Free Online Test One Mark Questions with Answer Key 2020 - Part Four

12th Standard EM

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Chemistry

Time : 00:25:00 Hrs
Total Marks : 25
25 x 1 = 25
1. Which of the following is used for concentrating ore in metallurgy?

(a)

Leaching

(b)

Roasting

(c)

Froth floatation

(d)

Both (a) and (c)

2. The basic structural unit of silicates is (NEET)

(a)

$\left( SiO_{ 3 } \right) ^{ 2- }$

(b)

$\left( SiO_{ 4 } \right) ^{ 2- }$

(c)

$\left( Sio \right) ^{ - }$

(d)

$\left( SiO_{ 4 } \right) ^{ 4- }$

3. Most easily liquefiable gas is

(a)

Ar

(b)

Ne

(c)

He

(d)

Kr

4. 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 assert

(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.

5. The coordination number of Ni(II) in [Ni(CN)4]2- is

(a)

2

(b)

4

(c)

5

(d)

0

6. The ionisation isomer of [Cr(H2O)4CI(NO2)]Cl is ____________

(a)

[Cr(H2O)4Cl2(NO)2]

(b)

[Cr(H2O)4Cl2]NO2

(c)

[Cr(H2O)4Cl(oNo)]

(d)

both (a) and (b)

7. The number of unit cells in 8 gm of an element X ( atomic mass 40) which crystallizes in bcc pattern is (NA is the Avogadro number)

(a)

6.023 X 1023

(b)

6.023 X 1022

(c)

60.23 X 1023

(d)

$\left( \cfrac { 6.023\times { 10 }^{ 23 } }{ 8\times 40 } \right)$

8. An excess of potassium ion makes KCl crystals appear violet since

(a)

Some of anionic sites are occupied by unpaired electron

(b)

Anionic sites are occupied by pair of electrons

(c)

both (a) and (b)

(d)

neither (a) nor (b)

9. The rate constant of a reaction is 5.8X10-2. The order of the reaction is

(a)

First order

(b)

zero order

(c)

Second order

(d)

Third order

10. In any unimolecular reaction _______________

(a)

Only two reacting species is involved in the rate determining step.

(b)

The order and the molecularity of slowest step are equal to one.

(c)

The molecularity of the reaction is one and order is zero.

(d)

Both molecularity and order of the reaction are one.

11. A certain current liberated 0.504gm of hydrogen in 2 hours. How many grams of copper can be liberated by the same current flowing for the same time in a copper sulphate solution

(a)

31.75

(b)

15.8

(c)

7.5

(d)

36.5

12. λc = μc for,

(a)

NaCI

(b)

H2SO4

(c)

Na2SO4

(d)

Al2(SO4)3

13. A substance which destroys the activity of a catalyst is________

(a)

negative catalyst

(b)

catalytic poison

(c)

both (a) and (b)

(d)

promoter

14. Assertion : Phenol is more acidic than ethanol
Reason: Phenoxide ion is resonance stabilized

(a)

if both assertion and reason are true and reason is the correct explanation of assertion.

(b)

if 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. With concentrated sulphuric acid, glycol undergoes intermolecular dehydration to give cyclic compound

(a)

diethylene glycol

(b)

dioxan

(c)

paraldehyde

(d)

glyoxal

16. The reaction of Lucas reagent is fast with

(a)

(CH3)3 COH

(b)

(CH3)2 CHOH

(c)

CH3(CH2)2OH

(d)

CH3CH2OH

17. Identify 'X'.

(a)

(b)

(c)

(d)

18. In Friedel Craft's reaction of benzoylation of benzene, which of the following acts as a electrophile?

(a)

CHCO+

(b)

CHO-

(c)

CH3CO+

(d)

CH3CO-

19. On Kolbe's electrolysis, formic acid gives

(a)

H2

(b)

methane

(c)

ethane

(d)

none

20. Reduction of RCHO to RCH3 by N2H4 in C2H5ONa is _________ reaction.

(a)

Stephen reduction

(b)

Catalytic reduction

(c)

Clemmensen reduction

(d)

Wolff-kishner reduction

21. Which among the following reactions will not result in the formation of carbon - carbon bond?________.

(a)

Friedel Craft

(b)

Cannizaro reaction

(c)

Riemer - Tiemann

(d)

None of the above

22. Benzoic acid, when heated with soda lime gives _________.

(a)

C6H5COONa

(b)

C6H5COOC6H5

(c)

C6-C6

(d)

C6H5OH

23. Complete the reaction $\underset { \overset { | }{ { CH }_{ 3 }-CHOH } }{ { CH }_{ 3 }-CHOH } \overset { { HIO }_{ 4 } }{ \underset { ? }{ \longrightarrow } } X$ is _________.

(a)

CH3COCH3

(b)

CH3CHO

(c)

C6H5CHO

(d)

${ CH }_{ 3 }-\underset { \overset { | }{ { CH }_{ 3 } } }{ C } -CH-CHO$

24. Identify X in the sequence give below

(a)

(b)

(c)

(d)

25. (CH3)2 - CH - NO when boiled with HCI/H2O gives compound 'X'. Identify 'X'.

(a)

CH3COOH

(b)

(CH3)2C = 0

(c)

CH3CHO

(d)

CH3NO2