Chemistry Test-12

Modern detergents contain enzyme preparation of alkaliphiles. Detergents represent the largest industrial application of enzymes amounting to 25-30% of total sales of enzymes. The enzymes used in detergents must be cost-effective, safe to use and be able to perform the task in the presence of anionic and non-ionic detergents soaps, oxidants, etc at pH between 8-10.5 %. The chief enzymes used are proteases, α-amylase and sometimes cellulase.

Electronic configuration of Chromium (Cr).

Cr- 1s² 2s² 2p⁶3s²3p⁶4s¹3d⁵

The states of matter having no definite shape but definite volume is Liquid.

Gases do not have definite shape or volume, liquids have definite volume but no definite shape and solids have definite shape and volume. Water is a liquid hence it has definite volume but no definite shape.

Given \(C + O _2 \rightarrow CO _2, \quad \Delta H ^{\circ}=-x kJ \quad \ldots .\). (i)

\(2 CO _2 \rightarrow 2 CO + O _2, \Delta H ^{\circ}=-y kJ\quad \ldots\)(ii)

or \(CO _2 \rightarrow CO +1 / 2 O _2, \Delta H ^{\circ}=+\frac{y}{2} kJ\quad \ldots\)(iii)

By adding no. (i) and (iii) eq.

\(C + O _2+ CO _2 \longrightarrow CO _2+ CO +\frac{1}{2} O _2\)

\(C +\frac{1}{2} O _2 \longrightarrow CO\)

\(\Delta H ^{\circ}=\frac{y} { 2}-x=\frac{y-2 x}{2} kJ\)

Lead oxide reacts with carbon to form lead and carbon dioxide. The balanced chemical equation is:

\(2 \mathrm{PbO}(s)+\mathrm{C}(s) \rightarrow 2 \mathrm{~Pb}(s)+\mathrm{CO}_{2}(g)\)

Gain of oxygen is oxidation and loss of oxygen is reduction.Lead oxide loses oxygen. Hence, it is reduced. So the statement, “Lead oxide is getting reduced" is correct statement.

Lead gains oxygen. Hence, it is oxidised. The statement, “Lead is getting reduced.” is incorrect and carbon dioxide loses oxygen. Hence, it is reduced. So, the statement, “Carbon dioxide is getting oxidised.” is incorrect.

The elements or compounds of the metals which occur in nature in the earth crust are called minerals.Minerals are substances that are formed naturally in the Earth. They are usually solid, inorganic, have a crystal structure, and form naturally by geological processes. A mineral can be made of a single chemical element or more usually a compound. They can be metals as well as non-metals.

Oxygen is not a greenhouse gas.

A greenhouse gas is a gas that produces heat in the atmosphere as it increases. It also gets stuck in the environment and can not leave the internal layer of the Earth’s atmosphere. These gases introduce pollution because they contaminate the environment.Examples of greenhouse gases are carbon dioxides, methane, CFC, sulphur dioxide.Whereas oxygen, nitrogen, and argon are not examples of greenhouse gases.

Ethanol disolves in water because they form hydrogen bonding.

Maintenance-free batteries, now in use, in place of common batteries, haveelectrodes made of calcium-containing lead alloy.

Avogadro's Law states that equal volumes of two different gases, under the same conditions of temperature and pressure, contain an equal number of molecules.