Sponsor Area
Write the number of covalent bonds in the molecule of ethane.
The number of covalent bonds in the ethane molecule is seven.
Sponsor Area
List two tests for experimentally distinguishing between an alcohol and a carboxylic acid and describe how these tests are performed.
Litmus test: Take two strips of blue litmus paper. Place a drop each of the alcohol and carboxylic acid on these strips separately. The blue litmus paper turns red in the case of carboxylic acid and remains unchanged in the case of alcohol.
sodium carbonate test: Carboxylic acid on reaction with sodium carbonate give brisk effervescence but alcohol does not give this test.
Draw the electron-dot structure for ethyne. A mixture of ethyne and oxygen is burnt for welding. In your opinion, why cannot we use a mixture of ethyne and air for this purpose ?
When a mixture of ethyne and oxygen burnt together it gives clean flame with temperature of around 3000 C
However,
when ethyne is burnt with air, it gives a sooty flame. this is due to incomplete combustion because of limited oxygen. Thus such high temperature in not obtained for welding.
Two elements ‘P’ and ‘Q’ belong to the same period of the modern periodic table and are
in Group 1 and Group 2, respectively. Compare their following characteristics in tabular form:
(a) The number of electrons in their atoms
(b) The sizes of their atoms
(c) Their metallic character
(d) Their tendencies to lose electrons
(e) The formula of their oxides
(f) The formula of their chlorides
| Characteristic | Comparison |
| (a) The number of electrons in their atoms |
The number of electrons in Q is more |
| (b) The sizes of their atoms | The size of atom P is more than atom Q (P > Q). |
| (c) Their metallic character | P is more metallic than Q (P > Q). |
| (d) Their tendencies to lose electrons | P will lose electrons more easily than Q. |
| (e) The formula of their oxides |
Oxide of P is P2O. |
| (f) The formula of their chlorides | Chloride of P is PCl. Chloride of Q is QCl2. |
Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.
Atomic number of the element = 16
Electronic configuration = 2, 8, 6
The period number is equal to the number of shells which starts filling up in it.
The atom of an element has three shells. So, the period number is 3.
The atom of an element has six valence electrons in the outermost shell. So, the group number of the element will be 16 (6 + 10).
The valency of an element is determined by the number of valence electrons present in the outermost shell. The atom of an element has six valence electrons in the outermost shell, so the valency of the element is 2.
Sponsor Area
Mock Test Series
