Chemistry Test 139

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Chemistry Test 139

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Weekly Quiz Competition

Question 1
4 / -1

A saturated aqueous solution of sparingly soluble salt AB₃ has the vapour pressure 0.08 mm lesser than the vapour pressure 17.33 mm of solvent at 25^oC. The solubility product of AB₃ is :

A
1.087 x 10^-2

B
1.48 x 10^-4

C
5.35 x 10^-5

D
4.56 x 10^-4

Solution
Question 2
4 / -1

Photoelectric emission is observed from a surface for frequencies v₁ and v₂ of the incident radiation (v₁ > v₂). If the maximum kinetic energies of the photoelectrons in the two cases are in the ration l : k then the threshold frequency v₀ is given by :

A

B

C

D

Solution
Question 3
4 / -1

In the following electron dot structure calculate the formal charge from left to right nitrogen atom ?

A
-1 ,-1 , +1

B
-1 ,+1 , -1

C
+1 ,-1, -1

D
+1,-1 , +1

Solution

1.Left N
⇒ 5 - 4 - 1/2 (4) = - 1
2.Central N
⇒ 5 - 0 - 1/2 (8) = + 1
3.Right N
⇒ 5 - 4 - 1/2 (4) = - 1
Question 4
4 / -1

A 50 litre vessel is equally divided into three parts with the help of two stationary semi permeable membrane (SPM). The vessel contains 60 g H₂gas in the left chamber, 160 g O₂ in the middle and 140 g N₂ in the right one. The left SPM allows transfer of only H₂ gas while the right one allows the transfer of both H₂ and N₂. The final ratio of pressure in the three chambers.

A
4 : 7 : 5

B
5 : 4 : 7

C
7 : 4 : 5

D
5 : 7 : 4

Solution
Question 5
4 / -1

Acetamide is treated separately with the following reagents. Which of these would give methylamine ?

A
PCl₅

B
Sodalime

C
NaOH + Br₂

D
Hot, conc. H₂SO₄

Solution
Question 6
4 / -1

White fumes. Metal (M) can be

A
Li, Mg or Al

B
Li, Al or K

C
Na, K or Mg

D
Li, Na or K

Solution

Li, Mg and Al when burn in air produces nitrides whose hydrolysis will liberate NH₃. NH₃ gives white fumes with HCl.
Question 7
4 / -1

Copper ore is heated in a blast furnace after mixing with silica. Iron oxide slags off as iron silicate and copper is produced in the form of

A
Copper sulphate

B
Copper Silicate

C
Copper matte

D
Copper hydroxide

Solution

During smelting, the roasted ore is mixed with coke and silica in a small blast furnace. The changes occurring are

Most of
FeS is oxidised to ferrous oxide

FeO removed as slag
(slag) at the lowest point of furnace, motion mass is Cu₂S plus little FeS.
Question 8
4 / -1

The ionization isomer of [Cr(H₂O)₄Cl(NO₂)]Cl is

A
[Cr(H₂O)₄(O₂N)]Cl₂

B
[Cr(H₂O)₄CI₂](NO₂)

C
[Cr(H₂O)₄Cl(ONO)]Cl

D
[Cr(H₂O)₄Cl₂(NO₂)]. H₂O

Solution

Ionisation isomers are the complexes that produce different ions in solution, i.e, they have ions interchanged inside and outside the coordination sphere.
Cr(H₂O)₄CI(NO₂)]Cl and [Cr(H₂O)₄Cl₂](NO₂) have different ions outside the coordination sphere and they are isomers. Therefore, they are ionisation isomers.
Question 9
4 / -1

What is the pH of 0.01 M glycine solution ? For glycine

A
3.02

B
6.94

C
6.06

D
10.02

Solution

For glycine H₂N - CH₂ - COOH which can act as zwitter ion
Question 10
4 / -1

Which one of the following cannot be prepared from B₂H₆ ?

A
NaBH₄

B
B₂(CH₃)₄H₂

C
B₂(CH₃)₆

D
H₃BO₃

Solution

In diborane (B₂H₆) molecule, only four terminal hydrogen atoms are replaceable. The two bridge H - atoms can not be substituted. Hence B₂(CH₃)₆ cannot be prepared from B₂H₆.