From given, we have,

The side of a cubical watermelon is equal to the diameter of a spherical watermelon.

The volume of a cube = a³

The volume of a sphere = 4/3 πr²

Let us consider the radius of the sphere is "x"

Then, we get

The volume of a cube = (2x)³ = 8x³

The volume of a sphere = 4/3 πx²

let us take, x = 2 cm

Then, we have,

The volume of a cube = 8x³ = 8×2³ = 64

The volume of a sphere = 4/3 πx² = 4/3 × 3.14 × 2² = 16.74

Thus the cubical watermelon would occupy more space than the other

Third Estate: The 3rd estate of then French society was further divided into three categories. Big businessmen, merchants, court officials, lawyers, etc. belonged to the first category of 3rd estate. Peasants and artisans belonged to the second category. And small peasants, landless labours and servants belonged to third category, and were considered as the lowest class in the society. Members of the third state had to pay all types of taxes including tithes and taille.

The ‘crystal lattice’ is the pattern formed by the points and used to represent the positions of these repeating structural elements. The periodic structure of an ideal crystal is most easily described by a lattice. The crystal lattice is the array of points at the corners of all the unit cells in the crystal structure. The crystal lattice is the symmetrical three-dimensional structural arrangements of atoms, ions or molecules (constituent particle) inside a crystalline solid as points. It can be defined as the geometrical arrangement of the atoms, ions or molecules of the crystalline solid as points in space.

Constituent particles in ionic solids of the Crystalline Solids are anions (negatively charged) and cations (positively charged). An ion is surrounded by a typical number of opposite charges. For example, in NaCl, the Na+ ion is surrounded by 6 Cl- ions. Ions in these solids are held together by strong electrostatic forces. They have high melting and boiling points and are soluble in polar solvents but not in non-polar solvents.

CLASSIFICATION OF CRYSTALLINE SOLIDS:-

Based upon nature of constituent particles and binding forces present in them:-

1. Ionic Solids:- 

• In these solids constituent particles are positive and negative ions. (cation or anions). They are held together by strong columbic electrostatic forces of attraction examples are NaCl, CaCl2, MgCl2, BaCl2 etc.

Characteristics of ionic solids:-

1. They have high melting and boiling points
2. They are soluble in polar solvents but are insoluble in non polar solvents.
3. Due to strong electrostatic forces of attraction they are closely packed hence hard but they are brittle.

2. Molecular Solids:-

• In these solids the constituent particles are molecules on the nature of molecules they can further subdivided into following three types:-

1. Non polar molecular solids:-

• • The crystalline solids in which constituent particles are atoms of noble gases [helium, neon] or non polar molecules like [H2, Cl2, I2]

Their characters are:-

1. 1. They are soft due to weak intermolecular forces.
   2. They are non conductors of electricity. They have low melting and boiling points.

2. Polar molecular solids:-

• • The crystalline solids in which constituent particles are polar molecules like HCl, SO2 etc. the intermolecular forces of attraction are dipole – dipole forces of attraction.

Thus their characters are:-

1. 1. They are soft; they are non conductors of electricity.
   2. Their melting and boiling points are high then non polar solids. They exists gases or liquid at room temperature.

3. Hydrogen bonded – molecular solids:-

• • In these solids the constituent particles are which contain hydrogen atom linked to high electronegative atoms as N, O, F

Their characters are:-

1. 1. They exists as volatile liquids or gases at room temperature.
   2. They are non conductor of electricity.
   3. Their melting and boiling points are high.

3. Covalent or network solids:-

• In these crystalline solids the constituent particles are non metal atoms linked to adjacent atom by covalent bond throughout the crystal. They forms a network of covalent bonds and exists as giant molecules. Example: Diamond

Their main characteristics are:-

1. As covalent bond is strong and directional in nature, these solid are very hard and brittle.
2. They have extremely high melting points and decompose before melting.
3. They are insult of and do not conduct electricity one exception is graphite which is covalent solid but is soft and also a good conductor of electricity.

4. Metallic solids:-

• In natural the constituent particles are positively charged metal ions – and free electrons.
• They are formed of metal atoms which lose their valance electrons to left behind positively charged ions.
• These metal atoms are surrounded by the sea of electrons each metal atom contributes one or more electrons to this sea of electrons.
• The electrons are simultaneously attracted by the +ve ions and holds these +ve ions ether

Metallic bond:-

• The force that holds the metal ion together in the crystal is called metallic bond.

Properties of metallic solids:-

1. They possess high electrical and thermal conductivity.
2. They possess lusture and colour in some case due to presence of sea of free electrons.
3. They are highly malleable and ductile.
4. They are closely packed. They exhibit high melting points and high densities.

Most of the solids found in daily life and practice are crystalline in nature. For Example metals like silver, copper, and iron, non-metals like iodine, sulphur and iodine and several compounds like NaCl (Sodium Chloride/Common Salt) etc. fall into the category of crystalline solids. We know that attraction nature of constituent particle is mainly responsible for the existence of solids. On the basis of nature of force operating between constituent particles of matter, crystalline solids are classified into four categories, namely:

• Molecular Solids

• Ionic Solids

• Metallic Solids

• Network or Covalent Solids

Amorphous silicon is a photovoltaic material widely used for conversion of sunlight into electricity.
The glass used in making glassware, rubber used in making hot water bags and cotton candy are amorphous solids

Pseudo-solid- are solids which are considered to be solid though they resembles in many respects liquid. They flow very slowly at room temperature and are considered as super cooled liquids. Amorphous solids are considered to be pseudo solid for e.g. Glass.
 

(a) 

ANSWER

Displacement is the shortest distance travelled from the initial point to the final point. After half revolution the displacement is the length of the diameter which is equal to 2r. Hence the displacement is 2r.

Amorphous Solids

The solids in which the constituent particles of matter are arranged in a random manner are called amorphous solids. It is a non-crystalline solid with no proper arrangement of atoms in the solid lattice. In other words, we can define amorphous solids as materials which don’t have certain organized arrangement of atoms and molecules. Most solids are amorphous in nature and are utilized in many sectors as well. One of the most common examples of amorphous solids is glass, which is used widely in the manufacturing sector.

Crystalline Solids

The solids in which the constituent particles of matter are arranged and organized in a specific manner are called Crystalline Solids. These solids contain crystals in their structure and each crystal has definite geometry. Adding further, as crystalline solids have low potential energy, they are the most stable form of solids. Almost all solids fall in the category of crystalline solids including metallic elements (iron, silver, and copper) and non-metallic elements (Phosphorus, Sulphur, and iodine). Also several compounds like sodium chloride, zinc sulphide and naphthalene build crystalline solids.

HRD Minister Ramesh Nishank announced a major CBSE syllabus reduction for the new academic year 2020-21 on July 7 which was soon followed by an official notification by CBSE on the same.

Considering the loss of classroom teaching time due to the Covid-19 pandemic and lockdown, CBSE reduced the syllabus of classes 9 to 12 with the help of suggestions from NCERT.

The CBSE syllabus has been rationalized keeping intact the learning outcomes so that the core concepts of students can be retained.

Click on the given link:

<a data-toggle="collapse" href="http://cbseacademic.nic.in/Revisedcurriculum_2021.html#collapse12">Revised Languages - (Group-L)</a>

<a data-toggle="collapse" href="http://cbseacademic.nic.in/Revisedcurriculum_2021.html#collapse13">Revised Academic Electives - (Group-A)</a>

<a data-toggle="collapse" href="http://cbseacademic.nic.in/Revisedcurriculum_2021.html#collapse14">Co-Scholastic Areas</a>

<a data-toggle="collapse" href="http://cbseacademic.nic.in/Revisedcurriculum_2021.html#collapse15">Curriculum Deduction Details (Deleted Portion only for the purpose of Annual Examination-2021) This has to be read along with the revised syllabus and also with the Alternative Calendar of NCERT</a>