Chemistry 1 Marks Question

Methane and Methanol.

Na, Ca, Mg and Al

The conductivity of a solution is the conductance of ions present in a unit volume of the solution. The number of ions (responsible for carrying current) decreases when the solution is diluted. As a result, the conductivity of a solution decreases with dilution.

Mg > Al > Zn > Fe > Cu is decreasing order of their reactivity.

It is molar conductivity at infinite dilution or approaching zero concentration.

1. Mercury cell.
2. Fuel cell.
3. Lead storage battery.
4. Dry cell.

Zink is better than tin in protecting iron from corrosion because zink has more affinity to oxygen than tin. When is coated on iron layer then it reacts with oxygen if air to form a protective layer of zink oxide on iron which prevent the further reaction of iron with oxygen, and thus preventing the process of rusting. But in the case of tin, it(tin) does not react with oxygen thus it is less effective in preventing rusting.

The electrical potential difference set up between the metal and its solution is called electrode potential.

Normal hydrogen electrode (NHE).

A process in which a metal is connected with a more reactive metal which acts as anode and the metal to be protected acts as a cathode is known as cathodic protection.

On the addition of water, number of ions per unit volume decreases and therefore conductivity decreases.

Concentration of Mg 2+ and Ag+ ions in the solution and temperature.

Oxidation or reduction cannot take place alone. Moreover, electrode potential is a relative tendency and can be measured with respect to a reference electrode only.

1. Concentrated aqueous KOH solution.
2. Moist mercuric oxide (HgO) mixed with KOH.

Ions.

Alternating current is used to prevent electrolysis so that concentration of ions in the solution remains constant.

The arrangement of elements in the increasing or decreasing order of their standard reduction potentials is called electrochemical series.

No, absolute electrode potential of an electrode cannot be measured.

‘A’ will have negative polarity. ‘B’ will have positive polarity.

To complete the inner circuit and to maintain the electrical neutrality of the electrolytic solutions of the half-cells we use a salt bridge in a Galvanic cell.

As the reaction proceeds, concentration of ions in anodic half keeps on increasing while in the cathodic half it keeps on decreasing. Hence, their electrode potentials also keep on changing till ultimately they become equal and then e.m.f. of the cell becomes zero.

Conductivity depends upon salvation of ions present in the solution. The greater the salvation of ions, the lesser is the conductivity.

Anode is the electrode at which oxidation, i.e., loss of electron takes place. It is -ve terminal.