CBSE 11TH CHEMISTRY - Online Test

Answer : Option C
Explaination / Solution:

If the elements are arranged in the order of their increasing atomic weights, after a regular interval similiar properties of elements are repeated.

Answer : Option A
Explaination / Solution:

Thermodynamics deals with heat and its transformation from one form to another. The branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy.

Answer : Option C
Explaination / Solution:

Chemistry does not deal in explaining superconductivity.

*In superconducting materials the charecteristics of superconductivity appear when the temperature is lowered below a critical temperature.

*The onset of superconductivity is accompanied  by abrupt changes in physical properties which are more related to phase transitions of the material .

These aspects of  studies in properties of materials  are better related to studies in the fields of Physics , eventhough  principles involved in Chemistry & Physics go hand to hand. 

Answer : Option A
Explaination / Solution:

Dalton was developed the theory of the structure of matter and this theory is known as Dalton’s atomic theory. His research was based on experiments and also from law of chemical combination. Dalton’s atomic theory was quickly explained the many heretofore unexplained chemical phenomena. Dalton’s atomic theory quickly became the theoretical foundation in chemistry. Dalton’s atomic theory stated that: All the matter is made of atoms which are tiny particles and indivisible. All the given atom of the element is identical in mass, size, shape, and in other properties. All different elements have different types of atoms and also different in their mass, size, shape, and in other properties. All the atom of an element cannot be made or destroyed.

Answer : Option C
Explaination / Solution:

Environmental chemistry basically deals with the origin, transport, reaction and effects of various chemical species of natural or human origin in the environment. It is a part of environmental studies that deals with all other aspects and interactions of environment.

Answer : Option C
Explaination / Solution:

As Hydrogen has 1 electron which fills in orbital of s subshell of First Shell.

Answer : Option B
Explaination / Solution:

Lewis developed electronic theory of valence or theory of chemical bonding to explain the formation of chemical bond between the two atoms.

According to the electronic theory of valence, every atom tries to attain octet configuration (presence of eight electrons) in its valence shell by losing or gaining or by sharing of electrons. This is known as the "Octet Rule".

The electrostatic forces of attraction that holds the two oppositely charged ions together are known as "electrovalent bond".

Answer : Option D
Explaination / Solution:

in hybridization as % of 's'character increases electronegativity also increases.

more the s charater, more will be the electronegativity of that atom.

increasing order ofelectronegativity  with %s character is sp (50%) >  sp2(33.33%) >  sp3(25%)

Answer : Option A
Explaination / Solution:

Oxidation means addition of oxygen, removal of hydrogen, increase in oxidation number, addition of a electronegative element or removal of an electropositive element

​​​​​​The term oxidation was first used to describe chemical reactions in which oxygen was added to an element of a compound. Later on the term oxidation was extended to describe many more reactions which occurred without the use of even oxygen.

Addition of Oxygen: Oxidation is a chemical reaction in which oxygen is added to any chemical species (atom, ion or molecule). Example

2Mg + O2 → 2MgO

S + O2 → SO2

2CO + O2 → 2CO2

Na2SO3 + H2O2 → Na2SO4 + H2O

Removal of Hydrogen : Oxidation is a chemical reaction in which hydrogen is removed from any chemical species (atom, ion or molecule).

H2S + Cl2 → 2HCl + S

4HI + O2 → 2H2O + 2I2

4HI + MnO2 → MnCl2 + 2H2O + Cl2

Addition of an Electronegative Element: Oxidation is a chemical reaction in which an electronegative element is added into any chemical species (atom, ion or molecule).

Fe+ S → FeS (Oxidation of iron)

SnCl2 + Cl2→ SnCl4(Oxidation of stannous chloride)

2Fe + 3F2 → 2FeF3(Oxidation of iron)

Removal of an Electropositive Element: Oxidation is a chemical reaction in which an electropositive element is removed from any chemical species (atom, ion or molecule).

2KI + H2O2 → 2KOH + I2 (Oxidation of potassium iodide)

2K2MnO4 + Cl2 → 2KCl + 2KMnO4 (Oxidation of potassium manganate)

2KI + Cl2 → 2KCl + I2 (Oxidation of potassium iodide)

A substance which brings oxidation is known as oxidizing agentt

 

Answer : Option C
Explaination / Solution:

s block comprises of only two groups alkali metal group and alkaline earth metal groups