Chemistry Test 72

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Chemistry Test 72

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Weekly Quiz Competition

Question 1
4 / -1

At 700 K, the equilibrium constant K_p, for the reaction 2SO₃( g)⇌2SO2( g)+O₂ Is 1.8×10⁻³kPa. What is the numerical value in moles per liter of Kc for the reaction at the same temperature?

A
3.09 × 10^-7

B
4.09 × 10^-7

C
5.09 × 10^-7

D
6.25 × 10^-7

Solution
Question 2
4 / -1

IUPAC name of myrcene is

A
7-methyl-3-methyleneocta-1,6-diene

B
2-methyl-6-methyleneocta-2,4-diene

C
7-methyl-3-methyleneocta-1,4,6-triene

D
2-methyl-6-methyleneocta-1,7-diene

Solution

IUPAC name of myrcene is 7-methyl-3-methyleneocta-1,6-diene. Myrcene, or β-myrcene, is an alkene natural hydrocarbon. It is more precisely classified as a monoterpene. Monoterpenes are dimers of isoprenoid precursors, and myrcene is a significant component of the essential oil of several plants, including bay, cannabis, and hops. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is a key intermediate in the production of several fragrances. α-Myrcene is the name for the structural isomer 2-methyl-6-methylene-1,7-octadiene, which has not been found in nature and is little used.

Hence, the correct option is (A).
Question 3
4 / -1

The energy of activation for a reaction is 100KJmol⁻¹. The presence of a catalyst lowers the energy of activation by 75%. What will be the effect on the rate of reaction at 20^∘C, other things being equal?

A
Increases by 10 kJ mol^-1

B
Decreases by 10 kJ mol^-1

C
Remains unaffected

D
Cannot be predicted

Solution
Question 4
4 / -1

A catalyst is added to a reaction to increase the rate of reaction. Which of the following statements is correct?

A
A catalyst increases the activation energy between reactants and products and hence, lowers the potential energy barrier.

B
A catalyst provides an alternate pathway or reaction mechanism.

C
A catalyst alters G, Gibbs energy of reaction.

D
A catalyst changes the equilibrium constant of a reaction.

Solution

A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased as this alternative route has lower activation energy than the reaction route not mediated by the catalyst.

Hence, the correct option is (B).
Question 5
4 / -1

If ΔH is the change in enthalpy and ΔE, the change in internal energy accompanying a gaseous reaction, then

A
△H is always greater than ΔE.

B
ΔH<ΔE only if the number of moles of the products is greater than the number of moles of the reactants.

C
ΔH is always less than ΔE.

D
ΔH < ΔE only if the number of moles of products is less than the number of moles of the reactants.

Solution
Question 6
4 / -1

Na⁺, Mg⁺, Al³⁺ and Si⁴⁺ are isoelectronic, their ionic size will follow the order-

A
Na⁺ > Mg²⁺ < Al³⁺ < Si⁴⁺

B
Na⁺ < Mg²⁺ < Al³⁺ < Si⁴⁺

C
Na⁺ > Mg²⁺ > Al³⁺ > Si⁴

D
Na⁺ < Mg²⁺ > Al³⁺ < Si⁴⁺

Solution

More the nuclear charge on ion, electrons are more strongly attracted, and thus size decreases. Therefore the correct order is: Na⁺ < Mg²⁺ > Al³⁺ < Si⁴⁺. Thus, the smallest size is aluminum ion.

Hence, the correct option is (D).
Question 7
4 / -1

Which of the following complexes is correctly named?

A
K₃[Fe(CN)₆] : Tripotassium hexacyanoferrate(III)

B
K₄[Fe(CN)₆] : Potassium hexacyanoferrate(IV)

C
[Cu(NH₃)₄](NO₃)₂ : Tetraamminecuprate(II) nitrate

D
[Cr(NCS)₄(NH₃)₂]^- : Diamminetetrathiocyanatochromate(III) ion

Solution

The correct answer is: [Cr(NCS)₄(NH₃)₂]^- : Diamminetetrathiocyanatochromate(III) ion. Reinecke's salt is a chemical compound with the formula NH₄[Cr(NCS)₄(NH₃)₂]·H₂O. The dark-red crystalline compound is soluble in boiling water, acetone, and ethanol. The chromium atom is surrounded by six nitrogen atoms in an octahedral geometry. The NH₃ ligands are mutually trans and the Cr–NCS groups are linear. The salt crystallizes with one molecule of water.

Hence, the correct option is (D).
Question 8
4 / -1

The enthalpy of vaporisation of a substance is 8400 J mol⁻¹ and its boiling point is −173.15^∘C. The entropy change for vaporisation is:

A
84 Jmol⁻¹K⁻¹

B
21 Jmol⁻¹K⁻¹

C
49 Jmol⁻¹K⁻¹

D
12 Jmol⁻¹K⁻¹

Solution
Question 9
4 / -1

The calculated spin magnetic moment of gaseous Fe²⁺ is

A
4.90 µB

B
3µB

C
1.73µB

D
0

Solution
Question 10
4 / -1

Which of the following is true for the resultant polymer product formed, when molecules of phthalic acid react with molecules of glycerol?

A
Branch polymer

B
Cross-link polymer

C
Linear polymer

D
None of the mentioned

Solution

The reaction between phthalic acid and glycerol initially results in linear or branched polymer but, due to the trifunctionality of glycerol, ultimately cross-linking takes place between the molecules. A trifunctional monomer can be linked to two other molecules under appropriate conditions. Examples are :

A polyfunctional molecule can react with more than two other molecules to form the corresponding number of new bonds during the polymerization reaction.

Hence, the correct option is (D).

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Chemistry Test 72

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Chemistry Test 72

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Question 1

3.09 × 10-7

4.09 × 10-7

5.09 × 10-7

6.25 × 10-7

Solution

Question 2

7-methyl-3-methyleneocta-1,6-diene

2-methyl-6-methyleneocta-2,4-diene

7-methyl-3-methyleneocta-1,4,6-triene

2-methyl-6-methyleneocta-1,7-diene

Solution

Question 3

Increases by 10 kJ mol-1

Decreases by 10 kJ mol-1

Remains unaffected

Cannot be predicted

Solution

Question 4

A catalyst increases the activation energy between reactants and products and hence, lowers the potential energy barrier.

A catalyst provides an alternate pathway or reaction mechanism.

A catalyst alters G, Gibbs energy of reaction.

A catalyst changes the equilibrium constant of a reaction.

Solution

Question 5

△H is always greater than ΔE.

ΔH<ΔE only if the number of moles of the products is greater than the number of moles of the reactants.

ΔH is always less than ΔE.

ΔH < ΔE only if the number of moles of products is less than the number of moles of the reactants.

Solution

Question 6

Na+ > Mg2+ < Al3+ < Si4+

Na+ < Mg2+ < Al3+ < Si4+

Na+ > Mg2+ > Al3+ > Si4

Na+ < Mg2+ > Al3+ < Si4+

Solution

Question 7

K3[Fe(CN)6] : Tripotassium hexacyanoferrate(III)

K4[Fe(CN)6] : Potassium hexacyanoferrate(IV)

[Cu(NH3)4](NO3)2 : Tetraamminecuprate(II) nitrate

[Cr(NCS)4(NH3)2]- : Diamminetetrathiocyanatochromate(III) ion

Solution

Question 8

84 Jmol−1 K−1

21 Jmol−1 K−1

49 Jmol−1 K−1

12 Jmol−1 K−1

Solution

Question 9

4.90 µB

3µB

1.73µB

0

Solution

Question 10

Branch polymer

Cross-link polymer

Linear polymer

None of the mentioned

Solution

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3.09 × 10^-7

4.09 × 10^-7

5.09 × 10^-7

6.25 × 10^-7

Increases by 10 kJ mol^-1

Decreases by 10 kJ mol^-1

Na⁺ > Mg²⁺ < Al³⁺ < Si⁴⁺

Na⁺ < Mg²⁺ < Al³⁺ < Si⁴⁺

Na⁺ > Mg²⁺ > Al³⁺ > Si⁴

Na⁺ < Mg²⁺ > Al³⁺ < Si⁴⁺

K₃[Fe(CN)₆] : Tripotassium hexacyanoferrate(III)

K₄[Fe(CN)₆] : Potassium hexacyanoferrate(IV)

[Cu(NH₃)₄](NO₃)₂ : Tetraamminecuprate(II) nitrate

[Cr(NCS)₄(NH₃)₂]^- : Diamminetetrathiocyanatochromate(III) ion

84 Jmol⁻¹K⁻¹

21 Jmol⁻¹K⁻¹

49 Jmol⁻¹K⁻¹

12 Jmol⁻¹K⁻¹