Chemistry M.C.Q (1 Marks)

The process used to decompose compounds using electric current is called electrolysis.

Tin cans, used for storing food, are made by electroplating tin onto iron. Tin is less reactive than iron. Thus, food does not come into contact with iron and
is protected from getting spoilt.

The presence of electrolyte increase the concentration of electron and thus increasing the mobility of electron due to which rate of corrosion increases.

In the activity series, metals are on the top of the series react and corrode easily as these metals are highly reactive like iron corrodes easily in the presence of water and air forming its oxide layer while metals present at the bottom are least reactive and do not corrode easily like gold, silver and platinum are some of them.

Impure metal will release electron hence form anode electrode and pure metal will absorb electron hence it will be posses as cathode electrode. Pure metal is used as the cathode and impure metal as anode.

According electron configuration of copper atom, there is one electron in the outermost shell. For becoming a stable atom, the copper electrode will donate electrons to hydrogen atom.

In photoelectric effect when monochromatic radiations of suitable frequency fall on the photo-sensitive plate called cathode, the photoelectrons are emitted which get accelerated towards the anode. These electrons flow in the outer circuit resulting in the photoelectric current.
Using the incident radiations of a fixed frequency, it is found that the photoelectric current increases linearly with the intensity of incident light.

Electrolytes which allow large current to pass through them are known as strong electrolytes.

At cathode reduction occurs, therefore, cathode acts as a reducing agent by supplying electrons.

Electrolytes which allow small amount of electricity to pass through them are known as weak electrolytes.

Inert electrode does not participate in redox reaction and acts only as source or sink for electrons. It provides surface either for oxidation or for reduction reaction.

During corrosion, the oxidation of metal to metal ions occur. Hence the metal undergoing corrosion acts as anode.

Internal resistance of a battery cell:

1. increases with increase in distance between two electrodes.
2. decreases with increase in concentration of electrolyte.
3. decreases with increase in area of the plate inside the electrolyte.
4. decreases with increase in size of the electrodes.

The weights of various ions liberated by passing the same current through different electrolytes are in the ratio of their Equivalent weights.

We know that when an atom donates electrons, the atom becomes positive charge and when the atom receives the electrons, it becomes negative charge.

Electrolysis is chemical decomposition produced by passing electric current through a liquid or solution containing ions.

Pure metals are resistive to corrosion. If there are impurities in a metal, a local galvanic cell is created with the metal as an anode and the impurity as a cathode. The result is the corrosion of the metal. And in the presence of a high concentration of oxygen, corrosion will be faster. Also when the conductivity of solutions is higher, the corrosion will be faster.

Voltiac cell, daniel cell, Lachanche cell, Bunsen cell, fuel are some well known example of primary battery cells. Whereas, lead acid cell and edison alkaline cell are two well known example of secondary cells.

An Anode is a positively charged electrode through which conventional current flows in a circuit.

Molar conductivity of ionic solution depends on temperature and concentration of electrolytes in solution.

It is an electrochemical cell which acts as a source of electrical energy without being previously charged up by an electric current from an external source of current.
In which electrode reactions cannot be reversed by an external source.
These are not chargeable.

Eectrolysis chemical decomposition produced by passing an electric current through a liquid or solution containing ions.The electrolysis proceeds and the rate of liberation remains the same happens when an electrolysis experiment is stopped and the battery terminals are reversed

Rusting of iron involves oxidation.

For lead accumulator battery, the oxidation reaction at anode requires two moles of electrons. Similarly, the reduction reaction at cathode requires two moles of electrons.

In an electrochemical cell, cathode is the electrode, at which reduction takes place and electrons are gained by some species.
Anode is the electrode, at which oxidation takes place and the electrons are lost by some species.

A electrolytic solution allows the flow of ions to maintain a balance in charge between the oxidation and reduction vessels while keeping the contents of each separate. With the charge difference balanced, electrons can flow once again, and the reduction and oxidation reactions can proceed.

The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating. It is one of the most common applications of chemical effects of electric current.
Electroplating is a very useful process. It is widely used in industry for coating metal objects with a thin layer of a different metal.

Corrosion resistance of aluminium is due to formation of thin layer of aluminium oxide that forms when metal is exposed to air and prevents further oxidation. It is called as protective passivation.

A secondary battery cell is one in which chemical energy is converted into electrical energy, but they work only when they are charged by passing electric current through them by some source.

A dry cell converts chemical energy into electrical energy.

A voltaic cell also known as galvanic cell is an electrochemical cell that uses spontaneous redox reactions to generate electricity. It consists of two separate half cells. Chemical energy is converted to electrical energy.

During electroplating by electrolysis, the article to be electroplated as made the cathode of an electrolytic cell.

Electrochemical cells or galvanic cells are same thing. Anode in galvanic cells is negative electrode where oxidation takes place.

The process of lead action in a simple voltaic cell is a chemical action that occurs while the current is flowing and causes hydrogen bubbles to form on the surface of anode. The action is called polarization. Some hydrogen bubbles rise to the surface of the electrolyte and escape into the air and some remain on the surface of the anode. If enough bubbles remain around the anode, the bubbles form a barrier that increases internal resistance. When the internal resistance of the cell increases, the output current is decreased and the voltage of the cell also decreases.

Electrolysis is the passing of a direct electric current through an ionic substance that is either molten or dissolved in a suitable solvent, producing chemical reactions at the electrodes and separation of materials. In metallic conductors, electrons carry the current and the material is unaffected by this flow for small currents.

In electrochemical corrosion. the metal undergoing corrosion acts as an anode.
In anode region, the metal is oxidized to metal cation and in cathode region, oxygen is reduced to water.

An electrolyte solution is formed by mixing an electrolyte in a solvent. The electrolyte on dissolution furnishes ions. The preferred movement of ions under the influence of the electric field is responsible for electric current. Hence, the electric current in a chemical cell is due to the movement of positive and negative ions.

Ionic substances can be broken down into the elements they are made from by passing electricity through them. The process is called electrolysis.

The Faraday constant represents the amount of electric charge carried by one mole, or Avogadro's number, of electrons.

Molten sodium and molten sulphur are used as electrodes in modern kind of battery because of high capacity and stable cyclic performance and stability.
They have highly active molten electrode.
Cathode typically made of molten sulphur and anode is sodium.

Corrosion can be prevented by creating a barrier between the object and oxygen. Galvanisation is a process to prevent corrosion and so is painting. However, exposing to sunlight is not a method to prevent corrosion.

Faradays laws are independent of temperature, or concentration Faradays laws are applicable at all concentrations.

Aluminium can be obtained from bauxite by Electrolysis. Bauxite is ore of Aluminium and Electrolysis is done to purify aluminium.

Solutions of acids and bases produce some ions that can carry electric current, so they are said to be electrolytes. Acids contain at least one hydrogen atom that can be removed when the acid is dissolved in water. An acid is a substance that produces hydrogen ions in a water solution. When an acid dissolves in water, hydrogen ions interact with water to form hydronium ions.
The strength of an acid or base depends on how many acid or base particles dissociate into ions in water. When a strong acid dissolves in water all molecules ionize into ions. When a weak acid dissolves in water a small fraction dissolve in water.

In an electrochemical cell, a redox reaction occurs. Oxidation occurs at one electrode and reduction occurs at another electrode. The reaction occuring at each electrode is known as half cell reaction.

A dry cell is a type of battery, commonly used for portable electrical devices.A standard dry cell comprises a zinc anode, usually in the form of a cylindrical pot, with a carbon cathode in the form of a central rod. The electrolyte is ammonium chloride in the form of a paste next to the zinc anode.Ammonium chloride is a strong electrolyte. In dry cell, the electrolyte ammonium chloride forms ammonium ion and chloride ions.

Bases ionizes in fused or in aqueous solution state and furnish ions in solution.

Oxidation takes place at anode and reduction at cathode. In electrolytic cell anode is positive and anode positive. In voltaic cell, anode is negative.
Metal deposition takes place in electrolytic cell only.
Direction of current is always cathode to anode in electrolytic cell.

In the electrolytic cell, the current flows from the cathode to anode in the outer circuit.
In the electrolytic cell, electrical energy is converted to chemical energy.

Electrolysis is a process by which electric current is passed through a substance to effect a chemical change i.e oxidation or reduction of a substance.

The metals lose their shine and become dull when exposed to air for a long time. Due to the formation of oxides, when the surface is rubbed by a sand paper, then the outer corroded layer is removed.

Electric energy is a form of energy, which is created by the movement of electrons. Generally electrons are bound to an atom by the positive force of protons. When for some reason these electrons get detached from their atoms electric energy is produced.

The compounds which decompose on passage of an electric current through them are known as electrolytes. e.g water, strong acids, strong bases.

Compounds should be aqueous or molten so that they can be easily dissociated into ions.

The energy conversion that takes place in a galvanic cell is an chemical to electrical change. Galvanic cells are cells that consist of two dissimilar metals in common contact with an electrolyte.

In an electrolytic cell cations move towards cathode and anions move towards anode. In the external circuit, current flows from anode to cathode.

Lower the value of standard reduction potential greater will be the reducing power.

In a galvanic cell, oxidation occurs at anode and reduction occurs at the cathode i.e., electrons are released from anode and they are accepted at the cathode. Hence, electrons flow from anode to cathode in a galvanic cell.

When the bulb is glowing, heat generates. Because of heat resistance of the filament increases. That is why the filament resistance of glowing bulb is greater than its resistance when it is not glowing.

Electrolysis is a method of using direct electric current to drive a chemical reaction. It involves the interchange of atoms and ions by the removal or addition of electrons.

Carbon dioxide is a weak electrophile. It possess very less partial positive charge which are attracted towards electrons.

Corrosion of the metal can be prevented if the contact between metal and air is cut of.

As we know, More negative is the standard potential, higher is the probability to oxidise and because of that it has high ability to displace hydrogen from acids.

The Zinc used in dry cell is which helps to maintain the moistness of paste contained in the cell between anode and cathode is highly hygroscopic.

When an impure metal is purified using electrolytic refining impure metal is used as anode and pure metal is used as cathode and the salt solution of same metal in pure form that is being purified is taken as electrolyte.

The decomposition of chemical compound in the aqueous or fused state by passing direct electric current is known as electrolysis.