Chemistry Test

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Chemistry Test - 12

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Weekly Quiz Competition

Question 1
4 / -1

The total number of ions present in 111 g of CaCl₂ is:

A
One Mole

B
Two Mole

C
Three Mole

D
Four Mole

Solution

Molecular weight of

CaCl₂ = 111 g/mol

Ions in one calcium chloride molecule = Ca⁺² + 2Cl^–

= 3 ions

Now no. of molecules in 111 g/mol of CaCl₂ = Avogadros number

= 6.02 × 10²³ molecules

So number of ions in 111 g/mol of CaCl₂

= 3 × 6.02 × 10²³ ions

= 3 moles.
Question 2
4 / -1

Which of the following is not an actinoid?

A
Curium (Z \(= 96\))

B
Californium (Z \(= 98\))

C
Uranium (Z \(= 92\))

D
Terbium (Z \(= 65\))
Solution
Terbium (Z \(= 65\)) is a lanthanide and all others are actinoids.
- Lanthanides have atomic numbers from \(58\) to \(71\).
- Actinides have atomic numbers from \(90\) to \(103\).
- The lanthanides and actinides form a group that appears almost disconnected from the rest of the periodic table.
- This is the f- block of elements, known as the inner transition series. This is due to the proper numerical position between Groups \(2\) and \(3\) of the transition metals.
Question 3
4 / -1

Which of the following is used as catalytic promoter?

A
Chlorine

B
Helium

C
Nitrogen

D
Sulphur

Solution

Promoters are the substances which when mixed with catalysts speed up the reaction.

Promoters are not capable of catalyzing a reaction alone but when mixed with catalysts, increases the efficiency of the catalysts.

Promoters increase the catalytic surface area and thus increases the efficiency of the catalysts.

For example, Molybdenum used in small amounts with Iron in Haber's Process increases the efficiency of finely divided iron.

Chromic oxide Cr₂O₃ is used as a promoter in water gas shift reaction with the catalyst Zinc Oxide.

Promoters are also known as Activators.

Nitrogen gas is extremely inert in nature and is used as a protective gas in many reactions to offer an inert environment for the reaction to occur.

Nitrogen is seen to act as a promoter in many reactions and promote the activity of Ru clusters.

It is now seen that Nitrogen can be activated in much less severe conditions.

Helium, Chlorine, and Sulphur are not used as promoters.

Nitrogen is used as a catalytic promoter.
Question 4
4 / -1

Which of the following properties are similar for isotopes?

A
Physical properties

B
Chemical properties

C
Both physical and chemical properties

D
Neither physical nor chemical properties

Solution

Isotopes have same atomic numbers but different mass numbers. This also means that the isotopes have the same number of electrons.

Chemical properties are determined by electronic configuration. So, with the same electronic configuration, they have similar chemical properties.
Question 5
4 / -1

The ionisation enthalpy of noble gases is_____________.

A
very low

B
very high

C
zero

D
none of these

Solution

The ionisation enthalpy of noble gases is very high as noble gases posses complete valence shell configurations. Hence energy required to remove an electron from valence shell of noble gas is the highest in a period.

Ionization enthalpy of an element can be defined as the amount of energy required to remove an electron from an isolated gaseous atom in its gaseous state.

Helium has the largest first ionization energy, while francium has one of the lowest.
Question 6
4 / -1

The final product \((C)\) obtained in the reaction sequence is \(C H_{3} C H_{2} C O O H \stackrel{P C l_{3}}{\longrightarrow}(A) \frac{C_{6} H_{6}}{A l C l_{3}}(B) \frac{N H_{2} N H_{2}}{\text { base, heat }}(C)\).

A

B

C

D

Solution

The reaction obtained is as follows:
Question 7
4 / -1

Detergents are prepared by the action of \(H_2SO_4\) on which of the following?

A
Cholesterol

B
Lauryl alcohol

C
Cyclohexanol

D
p-Nitrophenol

Solution

Detergents are prepared by the action of \(H_2SO_4\) on Lauryl alcohol.Dodecanol, or lauryl alcohol is an organic compound produced industrially from palm kernel oil or coconut oil. It is a fatty alcohol. Sulfate esters of lauryl alcohol specially sodium alcohol lauryl sulfate are very widely used as surfactants.

The chemical reaction is given as,

\(\underset{\text{Lauryl alcohol}}{\mathrm{CH} _3(\mathrm{CH} _2) _{10} \mathrm{CH} _2 \mathrm{OH}}+\mathrm{H} _2 \mathrm{SO} _4 \rightarrow \underset{\text{Lauryl hydrogen alcohol}}{\mathrm{CH} _3(\mathrm{CH}_ 2) _{10} \mathrm{CH} _2 \mathrm{OSO} _3 \mathrm{H}} ~{\overset{NaOH}{\longrightarrow}}~ \underset{\text{Anionic detergent}}{\mathrm{CH} _3(\mathrm{CH}_ 2)_{ 10 }\mathrm{CH}_ 2 \mathrm{OSO} _3-\mathrm{Na}^+}\)
Question 8
4 / -1

Which of the following statements are correct statement(s) about pyrophosphoric acid(\(\left.{H}_{4} {P}_{2} {O}_{7}\right)\)?

A
It contains \(P\) in +5 oxidation state

B
It is a dibasic acid

C
It is a reducing agent

D
It contains one \(\mathrm{P}-\mathrm{O}-\mathrm{P}\) bond

Solution

Structure of \(\mathrm{H}_{4} \mathrm{P}_{2} \mathrm{O}_{7}\) is shown in figure. Oxidation state of \(\mathrm{P}\) is +5 and it has one \(\mathrm{P}-\mathrm{O}-\) P bond.
Question 9
4 / -1

The heat change associated with reactions at constant volume is due to the difference in which property of the reactants and the products?

A
Internal energy

B
Enthalpy

C
Heat capacity

D
Free energy

Solution

The heat change associated with reactions at constant volume is due to the difference in the internal energy of the reactants and the products.

First Law of Thermodynamics dictates that \(\Delta \mathrm{Q}=\Delta \mathrm{U}+\Delta \mathrm{W}\)

At constant \(\mathrm{V}, \Delta \mathrm{W}=0\)

So, \(\Delta \mathrm{Q}=\Delta \mathrm{U}\)

So at constant volume, heat change takes place due to a change in the internal energy of the system.
Question 10
4 / -1

Of the following the most acidic is:

A
As₂O₃

B
P₂O₅

C
Sb₂O₃

D
Bi₂O₃

Solution

All the elements of the group 15 elements form tri oxides and pentoxides having the general formula M₂O₃ or M₂O₅.

The oxides of Nitrogen, Phosphorus, and Arsenic are acidic.

The trioxide of antimony Sb₂O₃ is amphoteric while that of bismuth Bi₂O₃ is basic.

As₂O₃ is acidic in nature.

The pentoxides of all these elements are acidic but acidic character decreases down the group.

Thus, P₂O₅is the strongest acidic oxide whereas Bi₂O₃ is the weakest acidic oxide.

The acidic character of the same element increases with an increase in the oxidation state.

Thus, the most acidic oxide among the following is P₂O₅.