Chemistry Test-7

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Chemistry Test-7

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Weekly Quiz Competition

Question 1
4 / -1

Pasteurization is related to:

A
Sterilization of milk

B
Dehydration of milk

C
Fermentation of milk

D
Distillation of milk
Solution
Pasteurization is related to sterilization of milk.

Pasteurization:
- Pasteurization is a process in which milk is treated with mild heat to eliminate pathogens and extend the shelf life of milk.
- Sterilization refers to any process that removes, kills, or deactivates all forms of life such as fungi, bacteria, spores, etc.
- Louis Pasteur invented the process of Pasteurization.
- Pasteurization of milk requires temperatures of about 63° C (145° F) maintained for 30 minutes or, alternatively, heating to a higher temperature, 72° C (162° F), and holding for 15 seconds.
Question 2
4 / -1

The exothermic formation of \(C l F_{3}\) is represented by the equation: \(C l_{2(g)}+3 F_{2(g)} \rightleftharpoons 2 C l F_{3(g)}\) ; \(\Delta H=-329 K J \) Which of the following will increase the quantity to \(ClF _{3}\) in an equilibrium mixture of \(Cl _{2}, F _{2} \) and \(ClF _{3}\) ?

A
Increasing the temperature

B
Removing \(C l_{2}\)

C
Increasing the volume of container

D
By adding \(F_{2}\)

Solution

The reaction given is an exothermic reaction.

number of moles of products are less than the number of moles of reactants. According to Le - chatalier's principle lowering of temperature, addition of \(F_{2}\) or \(Cl_{2}\) favours the forward reaction and hence the production of \(Cl F _{3}\). Increasing the volume of the container, the concentration of reactancts will decrease and the reaction will shift in backward direction.

So the correct answer is by addition\(F_{2}\).
Question 3
4 / -1

By using what can the colloidal particles can be separated from particles of the true solution?

A
Parchment paper

B
An ultracentrifuge machine

C
An electrolyte

D
Ordinary cloth

Solution

Centrifugation is a process that involves the use of centrifugal force for the sedimentation of heterogeneous mixtures with a centrifuge used in industry and in laboratory settings. This process is used to separate two immiscible liquids. Particles of colloids are big enough to be blocked by parchment paper or animal membrane.
Question 4
4 / -1

Which one has a pyramidal shape?

A
\(\mathrm{SO}_{3}\)

B
\(\mathrm{PCl}_{3}\)

C
\(\mathrm{CO}_{3}^{2-}\)

D
\(\mathrm{NO}_{3}{ }^{-}\)

Solution

\(\mathrm{PCl}_{3}\) has a pyramidal shape. In chemistry, a trigonal pyramid is a molecular geometry with one atom at the apex and three atoms at the corners of a trigonal base, resembling a tetrahedron (not to be confused with the tetrahedral geometry).
Question 5
4 / -1

According to Werner's theory of coordination compounds:

A
Primary valency is ionisable.

B
Secondary valency is ionisable.

C
Primary and secondary valencies are ionisable.

D
Neither primary nor secondary valency is ionisable.

Solution

Primary valency is ionisable according to Werner's theory of coordination compounds. According to Werner's coordination theory, there are two kinds of valency, primary and secondary. The primary valency of a central metal ion is satisfied with anions. For example, in \(\left[\mathrm{C u}\left(\mathrm{N} \mathrm{H}_{3}\right)_{4}\right] \mathrm{S} \mathrm{O}_{4}\) primary valency is \(2\) and secondary valency is \(4\) . Secondary valence refers to coordination number. Since copper is coordinated to \(4\) ammonia ligands, secondary valence is \(4\). Primary valence is satisfied by anions. Since sulphate ion has \(-2\) charge, primary valence is \(2 \).
Question 6
4 / -1

Which statement is false in regarding soaps?

A
Soaps used for cleaningpurpose are sodium or potassium salts of long chain fatty acids.

B
Soaps containing sodium salts areformed by heating fat.

C
Heating ofglyceryl ester of fatty acidwith aqueoussodium hydroxide solutionis known as saponification.

D
None of these

Solution

Soaps are the detergents used since long. Soaps used for cleaningpurpose are sodium or potassium salts of long chain fatty acids, e.g.,stearic, oleic and palmitic acids.
Question 7
4 / -1

In the froth flotation method, ore powder is placed in a tank filled with a mixture of:

A
Water and Aluminum

B
Water and Pine oil

C
Copper and Water

D
Water and Vegetable oil
Solution
In the froth flotation method, ore powder is placed in a tank filled with a mixture of water and pine oil.
- Froth flotation is an important concentration process that can be used to selectively separate hydrophobic materials from hydrophilic waste gangue.
- Froth flotation is one of the most popular operational processes for mineral beneficiation.
- In ore/mineral beneficiation, froth flotation is a method by which commercially important minerals are separated from impurities and other minerals by collecting them on the surface of a froth layer.
- Flotation is the process of separation of beneficial minerals from a mixture by creating froth on which minerals separate out.
- This method of froth floatation is a method of mineral processing in which different minerals are separated selectively.
- Such ores containing multiple metals such as lead, copper, and zinc can be selectively extracted by using froth floatation.
- The minerals that do not float into the froth are called the flotation tailings or flotation tails.
Question 8
4 / -1

Which of the following matchings is not correct?

A
\({sp}^{3}: {NH}_{3}:\) Pyramidal

B
\({sp}^{3} {d}: {PCl}_{5}:\) Trigonal bipyramidal

C
\({sp}^{3} {d}^{2}:\) \(XeF_{4}\) : Square planar

D
\({sp}^{2}:{AlCl}_{3}:\) Trigonal planar

Solution

We have to determine the hybridization of \(XeF_{4}\) :

Valence electron of \(Xe: 8\) & that of \(F:7\) (Here no. of \(F\) atom is \(4\))

So, total valence electron becomes \(7×4=28\).

Adding we get, \(8+28=36\)

Now, \(\frac{36 }{ 8}\) (quotient \(=4,\) remainder \(=4)\)

\(\Rightarrow\frac{Remainder }{2}\) \(=\frac{4 }{ 2}=2\)

Now, \(X=\) quotient \(+(\frac{ remainder }{2})=4+2=6\)

Now as from the above calculation hybridization of \(XeF_{4}\) is \(sp^{3}d^{2}\)and its structure is square planar.
Question 9
4 / -1

Which of the following is not a chain isomer of \(\ce{C6H14}\)?

A
\(\ce{2-Methylpentane}\)

B
\(\ce{2,2-Dimethylbutane}\)

C
\(\ce{3-Methylpentane}\)

D
\(\ce{2-Ethyl-3-methylbutane}\)

Solution

\(\ce{2-Ethyl-3-methylbutane}\) is not a chain isomer of \(\ce{C6H14}\).

Chain isomerism:

Chain, nuclear or skeleton isomerism: This type of isomerism arises due to the difference in the natureof the carbon chain (i.e., straight or branched) which forms the nucleus of the molecule. What is Hexane?

\(\ce{CH_{3} - CH_{2} - CH_{2} - CH_{2} - CH_{2} - CH_{3}}\)

The possible structures with same molecular formula with only difference in the nature of carbon chain will be:

\(\ce{2-Methylpentane}\):

\(\ce{2,2-Dimethylbutane}\):

\(\ce{n-Hexane}\):

\(\ce{3-Methylpentane}\):

\(\ce{2,3-Dimethyl butane}\):

Thus, \(\ce{2-Ethyl-3-methylbutane}\) is not belong from chain isomer of \(\ce{C6H14}\).
Question 10
4 / -1

The current inside a copper voltameter _________

A
is half the outside value.

B
is the same as the outside value.

C
is twice the outside value.

D
depends on the concentration of \(CuSO _4\)

Solution

The current inside a copper voltameter is the same as the outside value. An electric current is a flow of electric charge. In electric circuits, this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas (plasma). Electric current is measured using a device called an ammeter.