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#### 12th Standard Chemistry English Medium Free Online Test Volume 1 One Mark Questions 2020

12th Standard EM

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Chemistry

Time : 00:25:00 Hrs
Total Marks : 25
25 x 1 = 25
1. Which one of the following ores is best concentrated by froth – floatation method?

(a)

Magnetite

(b)

Hematite

(c)

Galena

(d)

Cassiterite

2. Pick out the alloy that contains a non-metal as a constituent in it

(a)

Brass

(b)

Bronze

(c)

Steel

(d)

Invar

3. The element that does not show catenation among the following p-block elements is

(a)

Carbon

(b)

silicon

(c)

(d)

germanium

4. In the brown ring test, brown colour of the ring is due to

(a)

a mixture of No and NO2

(b)

Nitroso ferrous sulphate

(c)

Ferrous nitrate

(d)

Ferric nitra

5. The correct order of increasing oxidizing power in the series

(a)

VO2+ < Cr2O72- < MnO4-

(b)

Cr2O72- < VO2+ < MnO4-

(c)

Cr2O72- < MnO4- < VO2+

(d)

MnO4- < Cr2O72- < VO2+

6. As per IUPAC guidelines, the name of the complex [Co(en)2(ONO)Cl]Cl is

(a)

chlorobisethylenediaminenitritocobalt(III) chloride

(b)

chloridobis(ethane-1,2-diamine)nitro  K-Ocobaltate(III) chloride

(c)

chloridobis(ethane-1,2-diammine)nitrito K-Ocobalt(II) chloridde

(d)

chloridobis(ethane-1,2-diamine)nitro K-Ocobalt(III) chloride

7. Structural formula of tetra aquadichlorideo Chromium (III) chloride.

(a)

[Cr(H2O)4Cl2]Cl2

(b)

[Cr(H2O)4Cl3]

(c)

[(H2O)4Cl2Cr]Cl2

(d)

[Cl2(H2O)4Cr]Cl3

8. Magnetic moment is given by the formula

(a)

$\sqrt { n(n+1) }$

(b)

$\sqrt { n(n+2) }$

(c)

$\sqrt { (n+2) }$

(d)

$\sqrt { { n }^{ 2 }+(n+2) }$

9. Assertion : monoclinic sulphur is an example of monoclinic crystal system
Reason: for a monoclinic system, $a\neq b\neq c$ and $\alpha =\gamma ={ 90 }^{ 0 },\beta \neq { 90 }^{ 0 }$

(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.

10. An example of covalent crystalline solid is ________

(a)

NaI

(b)

AI

(c)

Si

(d)

Ar

11. The coordination number of each sphere in body centred cubic packing is __________.

(a)

2

(b)

4

(c)

6

(d)

8

12. The addition of a catalyst during a chemical reaction alters which of the following quantities? (NEET)

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

13. For a reaction, 2A + B ⟶ 3C, The rate of appearance of C at time 't' is 1.2 x 10-4 mol L-1s-1. Identify the rate of reaction.

(a)

4 x10-5mol L-1s-1

(b)

4.5 x 10-1mol L-1s-1

(c)

3.6 x 10-4 mol L-1s-1

(d)

None of these

14. A+B $\longrightarrow$ C; ∆H = 60 kJ mol-1 Eaf = 150 kJ. What is the activation energy of the backward reaction?

(a)

210 kJ

(b)

105 kJ

(c)

90 kJ

(d)

145 kJ

15. Which order reaction obeys the expression ${ t }_{ \frac { 1 }{ 2 } }\alpha \frac { 1 }{ \left[ A \right] } ?$

(a)

First

(b)

Second

(c)

Third

(d)

Zero

16. The addition of a catalyst during a chemical reaction alters which of the following quantities?

(a)

Activation energy

(b)

Entropy

(c)

Internal energy

(d)

Enthalpy

17. How much time will be taken for 20 gm to reduce 5 g? [R = 2 x 10-3s-1 (I order reaction)]

(a)

693.1 s

(b)

693.1 s-1

(c)

6.931 s

(d)

6.931 s-1

18. Which of the above graphs is correct for zero order reactions?

(a)

I, II

(b)

I, III

(c)

I, IV

(d)

II, III

19. The excess energy which a molecule must possess to become active is known as

(a)

kinetic energy

(b)

threshold energy

(c)

potential energy

(d)

activation energy

20. The rate of a reaction is expressed as k[A]2[B]1,  the reaction is said to be

(a)

second order with respect to A

(b)

first order with respect to B

(c)

overall order of the reaction is third order

(d)

all the above

21. For a complex reaction ______________

(a)

Order of overall reaction is same as molecularity of the slowest step.

(b)

Order of overall reaction is less than the molecularity of the slowest step.

(c)

Order of overall reaction is greater than molecularity of the slowest step.

(d)

None of these above.

22. When the Ea of a reaction zero then the rate constant of the reaction is equal to __________

(a)

2.303 K

(b)

$\frac { K }{ 2.303 }$

(c)

$\left( { t }_{ \frac { 1 }{ 2 } } \right)$

(d)

A

23. For the reaction N2(g) + 3H2(g) ⟶ 2NH3(g) the rate of the reaction in terms of ammonia is __________________

(a)

$+\frac { 1 }{ 2 } \frac { -d\left[ { NH }_{ 3 } \right] }{ dt }$

(b)

$-\frac { 1 }{ 2 } \frac { d\left[ { NH }_{ 3 } \right] }{ dt }$

(c)

$\frac { -d\left[ { NH }_{ 3 } \right] }{ dt }$

(d)

$\frac { +d\left[ { NH }_{ 3 } \right] }{ dt }$

24. In a second order reaction, if one of the concentration is excess, the order of the reaction is _______________ order reaction.

(a)

first

(b)

pseudo first

(c)

third

(d)

zero

25. Activation energy of a reactant is reduced by ___________________

(a)

increased temperature

(b)

reduced temperature

(c)

increased pressure

(d)

reduced pressure