Chemistry Test

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Chemistry Test - 27

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Weekly Quiz Competition

Question 1
1 / -0

Which has least melting point?

A
Li

B
Na

C
K

D
Same for all

Solution

\(\begin{array}{cccc} & L i & N a & K \\ \text { Melting point }\left({ }^{0} C\right) & 180 & 98 & 64\end{array}\)
Hence, the correct option is (C)
Question 2
1 / -0

Which of the following will have the largest size in water?

A
Rb⁺

B
Na⁺

C
K⁺

D
Li⁺

Solution

Among the given ions, Li⁺ ion has the maximum charge density due to its small ionic size. Hence, it undergoes hydration to maximum extent. Thus, the size of hydrated Li⁺ ion is the maximum among the given ions.

Small size has high hydration energy.
Hence, the correct option is (D)
Question 3
1 / -0

Decreasing order of enol content of the following compounds in liquid/solution phase is:

A
2>1>3>4

B
1>2>3>4

C
4>3>2>1

D
3>1>2>4

Solution

The correct order is, 1>2>3>4. As phenol is aromatic (100% enol), then 2 will have a higher enol content because of acidic hydrogen.

Then 3 and 4. 4 is the least enolic due to higher stability of ketone.
Hence, the correct option is (B)
Question 4
1 / -0

How many optically active stereoisomers are possible for butan-2, 3-diol?

A
1

B
2

C
3

D
4

Solution

The number of optically active stereoisomers possible for 2,3−diol2,3−diol is 2. They are d,l isomers which are optically active. The meso- compound is optically inactive due to internal compensation. Hence, option B is correct.
Question 5
1 / -0

During estimation of nitrogen in the organic compound by Kjeldahls method, the ammonia evolved from 0.5 g of the compound in Kjeldahls estimation of nitrogen, neutralised 10 mL of 1M H₂SO₄. Find out the percentage of nitrogen in the compound.

A
14%

B
28%

C
56%

D
68%

Solution

In Kjeldahls method,

1M of 10ml H₂SO₄gives 1M of 20 ml NH₃

For 1000 ml of 1M NH₃ contains 14g of nitrogen gas

For 20 ml of 1M NH₃ contains (14/1000)×20g=0.28g of nitrogen gas

Percentage of nitrogen will be (0.28/0.5)×100=56%
Hence, the correct option is (C)
Question 6
1 / -0

PhCOOH and PhCH₃ can be separated by:

A
KMnO₄

B
aq. NaHCO₃+ n-hexane

C
H₂O

D
all of the above

Solution

PhCOOH dissolves in aq.NaHCO₃solution but toluene is not soluble in aq. NaHCO₃but dissolves in n-hexane.
Hence, the correct option is (B)
Question 7
1 / -0

Zeolite used to soften hardness of water is , hydrated :

A
Potassium aluminium borate

B
Sodium aluminium borate

C
Calcium aluminium borate

D
Zinc aluminium borate

Solution

Zeolites are complex inorganic salts like hydrated sodium aluminium silicates, Na₂Al₂Si₂O₈, which are used to remove the hardness of water.
Hence, the correct option is (B)
Question 8
1 / -0

Itching causing ______ crystals are found in colocasia leaves.

A
calcium carbonate

B
calcium oxalate

C
calcium sulphate

D
calcium chloride

Solution

Itching causing calcium oxalate crystals are found in colocasia leaves. Some varieties of raw or uncooked taro contain tiny crystals of a substance called calcium oxalate which causes itching. If taro is properly cooked, itching can be avoided.
Hence, the correct option is (B)
Question 9
1 / -0

The process which is employed to separate the ingredients of the mixture of two miscible liquids differing in their boiling points is:

A
fractional distillation

B
distillation

C
evaporation

D
decantation

Solution

Fractional distillation is the separation of a mixture into its component parts, or fractions, separating chemical compounds by their boiling point by heating them to a temperature at which one or more fractions of the compound will vaporize.
Hence, the correct option is (A)
Question 10
1 / -0

When solution of sodium chloride containing ethyl alcohol is electrolysed, it finally forms :

A
chloral

B
chloroform

C
ethyl chloride

D
acetaldehyde

Solution

Sodium chloride on electrolysis produces chlorine and chlorine oxidizes ethyl alcohol to acetaldehyde.

2NaCl→2Na+Cl₂

CH₃CH₂OH+Cl₂→CH₃CHO+2HCl
Hence, the correct option is (D)

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Chemistry Test - 27

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Chemistry Test - 27

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Question 1

Li

Na

K

Same for all

Solution

Question 2

Rb+

Na+

K+

Li+

Solution

Question 3

2>1>3>4

1>2>3>4

4>3>2>1

3>1>2>4

Solution

Question 4

1

2

3

4

Solution

Question 5

14%

28%

56%

68%

Solution

Question 6

KMnO4

aq. NaHCO3+ n-hexane

H2O

all of the above

Solution

Question 7

Potassium aluminium borate

Sodium aluminium borate

Calcium aluminium borate

Zinc aluminium borate

Solution

Question 8

calcium carbonate

calcium oxalate

calcium sulphate

calcium chloride

Solution

Question 9

fractional distillation

distillation

evaporation

decantation

Solution

Question 10

chloral

chloroform

ethyl chloride

acetaldehyde

Solution

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Rb⁺

Na⁺

K⁺

Li⁺

KMnO₄

aq. NaHCO₃+ n-hexane

H₂O