Chemistry Test-25

Result

Chemistry Test-25

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
4 / -1

For which change \(\Delta H \neq \Delta U\).

A
\(H_{2(g)}+I_{2(g)} \rightleftharpoons 2 H I_{(g)}\)

B
\(H C l_{(l)}+N a O H_{(l)} \rightarrow N a C l_{(l)}+H_{2} O_{(l)}\)

C
\(C_{(s)}+O_{2(g)} \rightleftharpoons C O_{2(g)}\)

D
\(N_{2(g)}+3 H_{2(g)} \rightarrow 2 N H_{3(g)}\)

Solution

Before we move ahead with the solution of this question, let us understand a few basic concepts.
\(\Delta H\) or change in enthalpy: This quantity accounts for the change in the total energy in the given reaction. To put it in simpler terms, it can be understood as the change in the energy states observed at two different instances in the reaction.
\(\Delta U\) or change in internal energy: Internal energy of a system can be identified as a thermodynamic property which represents the sum of the total kinetic energy and potential energy of the system. These kinetic and potential energies are associated with the random motion of the molecules present in the object. The internal energy of a sample is affected by the temperature of the system.
The relation between the enthalpy of a reaction and the internal energy of the system can be represented by the following formula:
\(\Delta H=\Delta U+\Delta n R T\)
Where n represents the number of moles of the substance, T is the temperature of the system and R is the gas constant. These factors directly affect the values of the enthalpy as well as the internal energy of the system. The values of enthalpy and internal energy would not be equal to each other until and unless either the change in the number of moles or the temperature is zero.
In the options given, let us consider that these reactions are carried out at constant temperature.
A. \(H_{2(g)}+I_{2(g)} \rightleftharpoons 2 H I_{(g)}\)
\(\Delta n=2-2=0\)
B. \({HCl}_{(l)}+{NaOH}_{(l)} \rightarrow {NaCl}_{(l)}+{H}_{2} {O}_{(l)}\)
\(\Delta n=2-2=0\)
C. \(C_{(s)}+O_{2(g)} \rightleftharpoons C O_{2(g)}\)
\(\Delta n=2-2=0\)
D. \(N_{2(g)}+3 H_{2(g)} \rightarrow 2 N H_{3(g)}\)
\(\Delta n=4-2=2\)
Therefore, \(\Delta H \neq \Delta U\) only in the last reaction.
Question 2
4 / -1

The reagent used for converting Acetylene tetrabromide into ethyne is:

A
Alcoholic KOH

B
Conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) at \(170^{\circ} \mathrm{C}\)

C
Aqueous potash

D
Zinc dust

Solution

Alcoholic KOH is used in preparation of acetylene from dihalides and Zn dust is used in preparation of acetylene from tetra halides.
Question 3
4 / -1

Assertion:
At equilibrium, vapour phase will be always rich in component which is more volatile.
Reason:
The composition of vapour phase in equilibrium with the solution is determined by the partial pressure of the components.

A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

C
Assertion is correct but Reason is incorrect

D
Both Assertion and Reason are incorrect

Solution

At equilibrium vapor phase will be always rich in component is more volatile.
The higher the vapor pressure of a liquid at a given temperature, the higher the volatility and the lower the normal boiling point of the liquid. The composition of vapor phase in equilibrium with the solution is determined by the partial pressure of the components.
Question 4
4 / -1

What is the radius of an atom used to measure?

A
Atomic number

B
Atomic mass

C
Atomic size

D
Atomicity

Solution

Atomic size: The atomic size depends on the number of electron orbits in the atom. The greater the number of orbits the larger the size.
Atomic radius is the distance between an atom's nucleus and its valence electrons.
It is measured in Angstroms(Å).
Atomic radius is used to determine the size of an atom.
When the atomic radius increases, the size of the atom also increases.
In the periodic table, the atomic radius increases down the group and decreases along a period from left to right.
Question 5
4 / -1

H₂O₂ acts as a reducing agent in

A
2FeCl₂+ 2HCl + H₂O₂ → 2FeCl₃ + 2H₂O

B
Cl₂ + H₂O₂ → 2HCl + O₂

C
2Hl + H₂O₂ → 2H₂O + l₂

D
H₂SO₃ + H₂O₂ → H₂SO₄ + H₂O

Solution

When H₂O₂(-1 oxidation state) serves as a reducing agent, the oxygen of H₂O₂is oxidized to O₂( 0 oxidation state) and bubbles are noticed. As a reducing agent:
Cl₂+ H₂O₂→ 2HCl + O₂
Therefore above reaction chlorine clearly changes to HCl.
Question 6
4 / -1

The hydrocarbon that cannot be prepared effectively by the Wurtz reaction is:

A

B

C

D

Solution

Wurtz reaction is a suitable method for the preparation of symmetrical alkanes only.
1,3-Dipropylcyclopentane can be obtained when a mixture of alkyl halides is used in the Wurtz reaction, and as a result, a mixture of products will be obtained.
So, the Wurtz reaction will not give a good yield of the product.
Question 7
4 / -1

Which statement is correct in regarding to chlordiazepoxide?

A
Chlordiazepoxide is used to relieve symptoms of anxiety.

B
Chlordiazepoxide is used to relieve symptoms ofnervousness before a surgery.

C
Both (A) and (B)

D
None of these

Solution

Chlordiazepoxide is used to relieve symptoms of anxiety, including nervousness or anxiety that happens before a surgery. It may also be used to treat symptoms of alcohol withdrawal.
Chlordiazepoxide is a benzodiazepine. Benzodiazepines belong to the group of medicines called central nervous system (CNS) depressants, which are medicines that slow down the nervous system.
This medicine is available only with your doctor's prescription.
Question 8
4 / -1

For irreversible expansion of an ideal gas underisothermal condition, the correct option is:

A

\(\Delta \mathrm{U} \neq 0, \Delta \mathrm{S}_{\text {total }}=0\)

B

\(\Delta \mathrm{U}=0, \Delta \mathrm{S}_{\mathrm{total}}=0\)

C

\(\Delta \mathrm{U} \neq 0, \Delta \mathrm{S}_{\text {total }} \neq 0\)

D

\(\Delta \mathrm{U}=0, \Delta \mathrm{S}_{\mathrm{total}} \neq 0\)

Solution

For a spontaneous process, \(\Delta \mathrm{S}_{\text {total }}>0\) and since irreversible process is always spontaneous therefore \(\Delta \mathrm{S}_{\text {total }}>0\).
Since \(\Delta \mathrm{U}=\mathrm{nC}_{\mathrm{V}} \Delta \mathrm{T}\) and \(\Delta \mathrm{T}=0\) for isothermal process therefore \(\Delta \mathrm{U}=0\).
Question 9
4 / -1

Elements of \(\mathrm{II^{nd }}\) period are known as _________.

A
Typical element

B
Bridge element

C
Transitional element

D
Normal element

Solution

Elements of \(\mathrm{II^{nd }}\) period are known as bridge element.
According to Mosley's periodic law, the physical and chemical properties of elements are periodic functions of their Atomic number.In the long-form periodic table, horizontal rows are called Periods and vertical rows are called groups.Bridge elements are the gap between the alkali and alkali earth metals (groups \(1\) & \(2\)) on one side and the metalloids/nonmetals (groups \(13\) - \(1\)8) on the other side.For example, Lithium and magnesium are showing similar properties, so second-period elements are known as Bridge elements.
Question 10
4 / -1

Which polymer is used in non-stick cooking vessels?

A
Polythene

B
Isoprene

C
Teflon

D
Neoprene

Solution

Teflon, which is the trade name for Polytetrafluoroethylene (PTFE), is the polymer used to deposit non-stick coatings on cookware.