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

12th Standard EM

Reg.No. :
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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. In the froth-floatation process the collectors such as pine oil and xanthates, etc enhance.

(a)

Non-wettability of the mineral particles in froth.

(b)

Non-wettability of the mineral particles in water

(c)

Non-wettability of the gangue particles in froth

(d)

Non-wettability of the gangue particles in water

3. The compound that is used in nuclear reactors as protective shields and control rods is

(a)

Metal borides

(b)

metal oxides

(c)

Metal carbonates d) metal carbide

(d)

none of these

4. An element belongs to group 15 and 3 rd period of the periodic table, its electronic configuration would be

(a)

1s2 2s2 2p4

(b)

1s2 2s2 2p3

(c)

1s2 2s2 2p6 3s2 3p2

(d)

1s2 2s2 2p6 3s2 3p3

5. Coinage metals are _________

(a)

normal metals

(b)

transition metals

(c)

active metals

(d)

alkali metals

6. Which type of isomerism is exhibited by [Pt(NH3)2Cl2]?

(a)

Coordination isomerism

(b)

(c)

Optical isomerism

(d)

Geometrical isomerism

7. Identify the Co-ordination entity in the given complex [Co(NH3)4(H2O)CI]CI2

(a)

Cl2

(b)

(NH3)4

(c)

[Co(NH3)4(H2O)Cl]

(d)

(H2O)

8. The crystal with a metal deficiency defect is

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

9. A crystal which has the same unit cell and contains the same lattice points throughout the crystal is_________.

(a)

perfect

(b)

imperfect

(c)

distorted

(d)

both (b) and (c)

10. Predict the rate law of the following reaction based on the data given below
$2A+B\longrightarrow C+3D$

 Reaction number [A] (min) [B] (min) Initial rate (M s-1) 1 0.1 0.1 x 2 0.2 0.1 2x 3 0.1 0.2 4x 4 0.2 0.2 8x
(a)

rate=k[A]2[B]

(b)

rate=k[A][B]2

(c)

rate=k[A][B]

(d)

rate=k[A]1/2[B]1/2

11. For an exothermic chemical process occurring in 2 steps as
(i) A +B ⟶ X (slow) ;
(ii) X ⟶  AB (fast)
The progress of the reaction can be best described by (x- intermediate).

(a)

(b)

(c)

(d)

None of these

12. Which one of the following is an example of pseudo first order reaction?

(a)

Acid hydrolysis of ester

(b)

Decomposition of HI

(c)

Synthesis of NH3

(d)

13. Conjugate base for bronsted acids H2O and HF are

(a)

OH- and H2FH+ , respectively

(b)

H3O+ and F, respectively

(c)

OH- and F-, respectively

(d)

H3O+ and H2F+, respectively

14. pH of 0.05M H2SO4 is

(a)

1

(b)

2.6990

(c)

1.3010

(d)

1.6990

15. Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because

(a)

Zinc is lighter than iron

(b)

Zinc has lower melting point than iron

(c)

Zinc has lower negative electrode potential than iron

(d)

Zinc has higher negative electrode potential than iron

16. The reciprocal of specific resistance is called _____________

(a)

conductance

(b)

specific conductance

(c)

conductivity

(d)

both specific conductance and conductivity

17. Which one of the is not a surfactant?

(a)

CH3 -(CH2)15 -N -(CH3)2 CH2Br

(b)

CH3 -(CH2)15 -NH2

(c)

CH3 -(- CH2- )-16CH2 OSO2- Na+

(d)

OHC-(CH2)14 -CH2 -COO- Na+

18. For W/O emulsion, the principle emulsifying agent is

(a)

proteins

(b)

synthetic soaps

(c)

lampblack

(d)

gums

19. Brownian movement of colloidal particles is a______property.

(a)

Kinetic

(b)

Electrica

(c)

Optical

(d)

Magnetic

20. In the reaction Ethanol $\overset { { PCl }_{ 5 } }{ \longrightarrow } X\overset { alc.KOH }{ \longrightarrow } Y\overset { { H }_{ 2 }{ SO }_{ 4 }/{ H }_{ 2 }O }{ \underset { 298k }{ \longrightarrow } } Z.$ The ‘Z’ is

(a)

ethane

(b)

ethoxyethane

(c)

ethylbisulphite

(d)

ethanol

21. Which of the following gives violet colour with neutral ferric chloride solution?

(a)

phenol

(b)

glycerine

(c)

benzyl alcohol

(d)

ethanol

22. The ultimate product obtained when glycerol reacts with oxalic acid at 533K is __________

(a)

formic acid

(b)

glycerol oxalate

(c)

allyl alcohol

(d)

acrolein

23. Which among the following does not give haloform test?

(a)

CH3CHO

(b)

CH3CO C2H5

(c)

CH3CH2 COCH2CH3

(d)

CH3CH2CO CH3

24. Acetone reacting with HCN to form cyanohydrin is ________ type of reaction.

(a)

(b)

Electrophilic substitution

(c)

(d)

Redox

25. CH3CHO and C6H5CH2CHO can be distinguished by ______.

(a)

Tollens reagent

(b)

Fehlings solution

(c)

Benedict

(d)

Iodoform test