Chemistry Test 289

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Chemistry Test 289

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Weekly Quiz Competition

Question 1
4 / -1

Which term refers to the spatial arrangement of ligands around the central metal ion?

A
Coordination entity

B
Coordination polyhedron

C
Coordination sphere

D
Ligand field

Solution

Coordination polyhedron describes the spatial arrangement of ligands around the central metal ion. Coordination sphere includes the central ion and ligands, while coordination entity is the entire complex ion.
Question 2
4 / -1

A
AgCN

B

C
Both have equal solubility

D
Cannot be determined

Solution

To determine which salt is more soluble, we need to calculate the molar solubility (s) for each from their respective solubility product constants (K_sp). A salt with a higher molar solubility is more soluble. It's important to note that we cannot directly compare K_sp values for salts that produce a different number of ions upon dissociation.

1. Solubility of AgCN

The dissociation of AgCN in water is:
Question 3
4 / -1

Which of the following elements does not exhibit typical transition metal properties despite being in the d-block?

A
Iron (Fe)

B
Zinc (Zn)

C
Copper (Cu)

D
Titanium (Ti)

Solution

Zinc (Zn) has the electronic configuration [Ar]3d¹⁰4s². Since it has a completely filled d-orbital (d¹⁰), it does not exhibit typical transition metal properties like variable oxidation states, paramagnetism, or formation of colored ions.

Fe, Cu, and Ti, on the other hand, show these properties due to their incomplete d-orbitals.
Question 4
4 / -1

Transition metals often act as catalysts in chemical reactions. This property is primarily due to:

A
Their high melting points

B
The presence of incomplete d-orbitals

C
Their ability to form colored compounds

D
Their metallic nature

Solution

Transition metals can form unstable intermediate compounds due to their variable oxidation states and incomplete d-orbitals, which facilitate the reaction process. This makes them effective catalysts.
Question 5
4 / -1

The correct order of boiling point for primary (1^o), secondary (2^o) and tertiary (3^o) alcohols is

A
1^o> 2^o> 3^o

B
3^o> 2^o> 1^o

C
2^o> 1^o> 3^o

D
2^o> 3^o> 1^o
Solution
- The boiling point of alcohols is influenced by hydrogen bonding and molecular weight. However, branching in carbon chains affects boiling points significantly.
- More branching leads to a more compact structure, which reduces the surface area available for intermolecular forces.
- Tertiary Alcohols (3^∘) : Due to the high degree of branching, tertiary alcohols have the lowest boiling points. The bulky structure reduces the ability to form hydrogen bonds effectively.
- Secondary Alcohols (2^∘) : These have moderate branching and thus have higher boiling points than tertiary alcohols but lower than primary alcohols.
- Primary Alcohols (1^∘) : With the least branching, primary alcohols can form stronger hydrogen bonds and have the highest boiling points among the three types.
- The correct order of boiling points for primary, secondary, and tertiary alcohols is: The correct order of boiling points for primary, secondary, and tertiary alcohols is: The correct order of boiling points for primary, secondary, and tertiary alcohols is: 1^∘> 2^∘> 3^∘
Question 6
4 / -1

An aqueous solution of a non-volatile solute has a freezing point of −0.186^∘C. If K_f= 1.86 K kg mol⁻¹ and K_b = 0.512 K kg mol⁻¹ for water, the elevation in boiling point ( ΔT_b ) for the same solution is:

A
0.186^∘C

B
0.0512^∘C

C
0.0186^∘C

D
0.512^∘C

Solution
Question 7
4 / -1

Amongst the following identify the species with an atom in + 6 oxidation state

A

B

C

D

Solution
Question 8
4 / -1

Which reagent can be used to distinguish between 1-butyne and 2-butyne?

A
NaNH₂

B
HCl

C
Br₂/ CCl₄

D
Cold KMnO₄

Solution

1-butyne is a terminal alkyne with an acidic hydrogen atom on the triple-bonded carbon, which reacts with strong bases like NaNH₂ to form a salt. 2-butyne is an internal alkyne and lacks this acidic hydrogen.
Question 9
4 / -1

The number of π bonds in 3-hexyne-1-ene is

A
1

B
2

C
3

D
4

Solution

The name 3-hexyne-1-ene indicates a 6-carbon chain with a double bond at carbon 1 and a triple bond at carbon 3. The carbons are numbered from the end that gives the lowest locants to the multiple bonds. The structure of 3-hexyne-1-ene is:
Question 10
4 / -1

The number of molecules in 16 g of methane is

A
3.0 × 10²³

B
6.02 × 10²³

C
16 / 6.02 × 10²³

D
16 / 3.0 × 10²³

Solution

6.02 × 10²³ Methane is CH₄; its molar mass is 12 g (C) + 4×1 g (H) = 16 g mol⁻¹. Therefore 16 g of methane equals exactly 1 mole. By Avogadro’s constant, 1 mole of any substance contains 6.02 × 10²³ molecules.