The best position of hydrogen in the periodic table is above IA group. What is the reason?

In the classification of elements in the periodic table, hydrogen is placed at the top of IA group. It has many similarities with the group elements.

It is false that electron affinity

When an element gives off its electron and forms a positive ion, it is called electropositivity of that element.

X + e-= X^- + energy

The most reactive element among group 17 will be

Among the halogen family, if we observe the values like ionisation energies, electron affinity and electronegativity, we can predict the reactivity of an element among the group. As we see the trend, all the values decrease down the group.

At STP, which substance is the best conductor of electricity?

Conductivity refers to the ability of a material to transmit energy. There are different types of conductivity, including electrical conductivity and thermal conductivity.

Hydrogen resembles with carbon because of

₁H^1- hydrogen belongs to first group of periodic table with the electronic configuration of 1s^1.

₆C¹²- carbon belongs to p-block and electronic configuration is 1s²2s²2p^4.

Which of the following elements would lose an electron easily?

 X(g)------------->X⁺ + e^-

Which set of elements contains a metalloid?

Metals are generally hard, shiny and malleable. They are good conductors. Examples of metals are gold, silver, iron, uranium and zinc.

Non-metals are brittle and are not easily molded into shapes. They are poor conductors of heat and electricity. Examples of non-metal elements are hydrogen and carbon.

Metalloids share characteristics of both metals and non-metals and are also called semi-metals. Metalloids are typically semi-conductors, which means that they both insulate and conduct electricity. This semi-conducting property makes them very useful as a computer chip material. Examples of metalloid elements are silicon and boron.

Down a group, electron affinity

The amount of energy released when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion:

 X + e⁻ → X⁻ + energy

The element with the highest electron affinity is

When an atom gains electron, energy is given off and this energy is known as electron affinity for that particular atom or molecule. Electron affinity is defined as the energy released when an electron is added to a gaseous atom or ion. 

T + e- =  T-

Cl + e^--= Cl^1- 

(Ne)3s²3p⁵------>(Ne)3s²3p⁶

What affects the ionisation energy of an element?

X   +  energy---->  X⁺ + e^-

Which of the following factors does not effect the metallic character of an element?

When an element shows properties like loosing electrons easily, getting reduced easily, formation of ionic halides and basic oxides and has the ability to displace hydrogen from dilute acids, it is considered to be a metal. Metallic character decreases across a period. This occurs because atoms accept electrons more readily to fill the valence shell than loosing one. Metallic character increases while moving down a group because atoms lose electrons more easily because of the increase in the atomic radii, resulting in decrease in the attraction between nucleus and valence electrons.

Five elements A, B, C, D and E have the following atomic numbers. Among these elements, which element belongs to third period and has the highest ionisation potential?

The minimum amount  of energy is required to pull out an electron from an atom or molecule in the gaseous state.
The first ionisation energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions, each with a charge of 1^+.

X_(g)------------>X⁺+e^-
It is the energy needed to carry out this change per mole of X.

Which of the following does not increase while moving towards higher groups?

Periodic properties of chemical elements reoccur periodically. This is the basis of creation of periodic table. In the classification of elements, elements show a periodic trend in many properties. The main basis of classification of these elements is increasing atomic number, which represents increasing positive charge in the nucleus. Negatively charged electrons are arranged in orbitals around the nucleus. The recurring properties of these elements are due to recurring configurations of these electrons in the orbitals around the nucleus.

The element which has zero electron affinity in the third period is

When an electron is added to a neutral atom in the gaseous state, certain amount of energy is released. During this process, this energy is called electron affinity of that particular atom.

 X + e^-----> X ^-

For explanation to this question, first electronic configurations of all these elements have to be taken into consideration.

An atom of which of the following elements has the greatest ability to attract electrons?

The ability of attracting electrons of any element is called electronegativity of that element. Electronegativity is affected by both its atomic number as well as the distance between its nucleus and the valence shell electrons. The higher the value of electronegativity, more electrons get attracted. It is a dimensionless quantity, commonly referred to as the Pauling scale on a relative scale starting from 0.7 to 3.98.