Questions

A Scalar quantity is a quantity that has only magnitude but no direction as like vector. 

Here in the given options, electric current is the only one which is scalar.

Atomic  number  is  the  fundamental properties  of  an  element.  Every atom  is  identified  by  its  unique atomic  number.  Atomic  number  is equal  to  the  number  of  protons present in an atom of the element.

In physics, we know that the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity.

Hence, An object that has kinetic energy must be in motion i.e, moving.

Pollination by wind is called Anemophily or Wind pollination. The process of the transfer of pollen from one individual plant to another, whereby the pollen is carried by air currents is called Anemophily.

Almost all gymnosperms (Non-flowering plants) are anemophilous, as are many plants in the order Poales, including grasses, sedges and rushes.

Graphite is a covalent-network type of crystalline solid.

There are two main categories of solids.

1. Crystalline solids and

2. Amorphous solids.

Crystalline solids are those in which the atoms, ions, or molecules that make up the solid exist in a regular, well-defined arrangement.

There are four types of crystalline solids :

Ionic solids :— Made up of positive and negative ions and held together by electrostatic attractions. They’re characterized by very high melting points and brittleness and are poor conductors in the solid state. An example of an ionic solid is table salt, NaCl.

Molecular solids :— Made up of atoms or molecules held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. Characterized by low melting points and flexibility and are poor conductors. An example of a molecular solid is sucrose.

Covalent-network (also called atomic) solids :— Made up of atoms connected by covalent bonds; the intermolecular forces are covalent bonds as well. Characterized as being very hard with very high melting points and being poor conductors. Examples of this type of solid are diamond and graphite, and the fullerenes. As you can see below, graphite has only 2-D hexagonal structure and therefore is not hard like diamond. The sheets of graphite are held together by only weak London forces!

Metallic solids :— Made up of metal atoms that are held together by metallic bonds. Characterized by high melting points, can range from soft and malleable to very hard, and are good conductors of electricity.