M.C.Q-[Che-1M]

MCQ 11 Mark

Plaster of Paris hardens by

A
Passing of $\mathrm{CO}_{2}$ gas
B
Changing into $\mathrm{CaCO}_{3}$
✓
Combining with water
D
Releasing out a molecule of water

Answer

Correct option: C.

Combining with water

(C) Combining with water
Explanation :
When water is added to the Plaster of Paris, it sets into a hard mass due to its hydration to form crystals of gypsum.
$\mathrm{CaSO}_{4} \cdot \frac{1}{4} \mathrm{H}_{2} \mathrm{O}+1 \frac{1}{2} \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}$

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MCQ 21 Mark

The correct formula of ethanol is:

A
$\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{OH}$
✓
$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$
C
$\mathrm{CH}_{3} \mathrm{OH}$
D
$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$

Answer

Correct option: B.

$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$

(B) $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$
Explanation :
$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$

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MCQ 31 Mark

Match the following with the correct response :

Column A	Column B
(i) Ionic bond	(a) $\mathrm{NH}_{3}$
(ii) Polar covalent bond	(b) $\mathrm{C}_{60}$
(iii) Non-polar bond	(c) $\mathrm{N}_{2}$
(iv) Fullerene	(d) NaCl

A
(i) - (c), (ii) - (b), (iii) - (d), (iv) - (a)
✓
(i) - (d), (ii) - (a), (iii) - (c), (iv) - (b)
C
(i) - (b), (ii) - (d), (iii) - (a), (iv) - ©
D
(i) - (a), (ii) - (c), (iii) - (b), (iv) - (d)

Answer

Correct option: B.

(i) - (d), (ii) - (a), (iii) - (c), (iv) - (b)

(B) (i) - (d), (ii) - (a), (iii) - (c), (iv) - (b)
Explanation :
- NaCl has ionic bonds between the sodium ion and the chloride ion.
- Ammonia has polar covalent bonds between the nitrogen atom and hydrogen atoms.
- Nitrogen molecule has non-polar covalent bonds between the two nitrogen atoms since the two atoms are alike.
- $\mathbf{C}_{\mathbf{6 0}}$ is a member of fullerenes (Allotropes of carbon). Buckminsterfullerene contains a cluster of 60 carbon atoms joined together to form spherical molecules.

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MCQ 41 Mark

The slag obtained during the extraction of copper pyrites is composed mainly of :

A
$\mathrm{CuSiO}_{3}$
B
$\mathrm{SiO}_{2}$
C
$\mathrm{Cu}_{2} \mathrm{~S}$
✓
$\mathrm{FeSiO}_{3}$

Answer

Correct option: D.

$\mathrm{FeSiO}_{3}$

(D) $\mathrm{FeSiO}_{3}$
Explanation :
The sulphide ore of copper-containing iron is mixed with silica before heating in a reverberatory furnace. Iron oxide forms a slag of iron silicate $\left(\mathrm{FeSiO}_{3}\right)$.
The reaction is: $\mathrm{FeO}+\mathrm{SiO}_{2} → \mathrm{FeSiO}_{3}$

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MCQ 51 Mark

The melting point of NaCl is:

A
1047 K
B
100 K
C
1000 K
✓
1074 K

Answer

Correct option: D.

1074 K

(D) 1074 K
Explanation :
The melting point of NaCl is $801^{\circ} \mathrm{C}$ or 1074 K .

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MCQ 61 Mark

Soap doesn't work well with woollen garments because :
A. It is basic in nature and woollen garments have acidic dyes.
B. It is acidic in nature and woollen garments have basic dyes.

✓
(A)
B
(B)
C
None of these
D
Both (A) and (B)

Answer

Correct option: A.

(A)

(A) (A)
Explanation :
Soap is basic in nature. Acid dyes are used to dye protein fibres such as silk, wool, angora, mohair, feathers, etc. Hence, soap doesn't work well with woolen garments. The soap gets neutralized by the acidic dyes.

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MCQ 71 Mark

When sodium hydrogen carbonate is added to ethanoic acid a gas evolves.
Consider the following statements about the gas evolved?
A. It turns lime water milky.
B. It is evolved with a brisk effervescence.
C. It has a smell of burning sulphur.
D. It is also a by-product of respiration.
The correct statements are:

A
(B) and (D) only
B
(A) and (B) only
✓
(A), (B) and (D)
D
(A), (C) and (D)

Answer

Correct option: C.

(A), (B) and (D)

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