Four sectors of the economy as follows:

1. Producer sector: It includes those involved in productive activities. It includes all producing firms in the economy. To produce goods and services, the firm hires the factors of production from the households.
2. Government sector: It acts as a welfare agency involved in maintaining law and order, defence and other services of public welfare. It also produces goods and services in public sector enterprises.
3. Household sector: It includes consumers of goods and services and also the owners of factors of production.
4. External sector: It involves in export and import of goods and the flow of capital between the domestic economy and other countries of the world.

In biology, a part of the cell cycle in which cells divide (mitosis) and/or reproduce (meiosis). In eukaryotes, the cell cycle consists of four discrete phases: G1, S, G2, and M. The S or synthesis phase is when DNA replication occurs, and the M or mitosis phase is when the cell actually divides. Mitosis is the process in which the nucleus of a eukaryotic cell divides. During this process, sister chromatids separate from each other and move to opposite poles of the cell. This happens in four phases, called prophase, metaphase, anaphase, and telophase.

On July 7, HRD Minister Ramesh Pokhriyal announced a major CBSE syllabus reduction with 30% of the syllabus slashed for the year 2020-21 for classes 9 to 12 because of the reduction in classroom teaching time due to the Covid-19 pandemic and lockdown.

CBSE has rationalized the syllabus with the help of suggestions from NCERT and the same has been notified by a new CBSE notification as well.

Click on the given link:

<a data-toggle="collapse" href="http://cbseacademic.nic.in/Revisedcurriculum_2021.html#collapse1">Revised Senior Secondary Curriculum (XI-XII)</a>

Cinchona tree which was used to make medicine for Malaria disappears from Kerala. As the technology to extract medicine from the bark of cinchona was developed, the tree was farmed widely all over the world.

The president of The United Nations Educational, Scientific and Cultural Organization is Audrey Azoulay
The 39th session of UNESCO's General Conference elected Audrey Azoulay as Director-General of UNESCO, succeeding Irina Bokova.

Taking selfies has become a rage and is a global phenomenon. it is it has cost us several lives and also immortalized several moments .write an article for a national daily on the trend of taking selfies and its impact on people.​

Isokinetic exercises : This is a type of muscle contraction where both the tension and speed are prefixed throughout the range of motion. This process involves development of maximum tension in muscles which shortens at constant speed at all angles.

As per Partnership Act, in the absence of partnership agreement, interest on partners loan is allowed at 6% p.a. A and B having contributed larger amounts of capital, desire that the profits should be divided in the ratio of their capital contribution but C does not agree.

Van der Waals forces are weak intermolecular forces that are dependent on the distance between atoms or molecules. These forces arise from the interactions between uncharged atoms/molecules.

For example, Van der Waals forces can arise from the fluctuation in the polarizations of two particles that are close to each other

Electron gain enthalpy of an element may be defined as the energy released when a neutral isolated gaseous atom accepts an extra electron to form the gaseous negative Ion i.e. anion.It is denoted by

 Δ eg H.

Greater the amount of energy released in the above process, higher is the electron gain enthalpy of the element. The electron gain enthalpy of a element is a measure of the firmness or strength with which an extra electron is bound to it.

Electron gain enthalpy is measured in electron volts per atom or kJ per mole.

The process of adding an electron to the atom can be either exothermic or endothermic.

Energy is released when an electron is added to the atom. Therefore, the electron gain enthalpy is negative.

The electron gain enthalpy for halogens is highly negative because they can acquire the nearest stable noble gas configuration by accepting an extra electron.

Noble gases have large positive electron gain enthalpy because the extra electron has to be placed in the next higher principal quantum energy levels there by producing highly unstable electronic configuration.

After the addition of 1 electron, the atoms becomes negatively charged and the second electron is to be added to a negatively charged Ion. But the addition of second electron is opposed by the electrostatic repulsion and hence the energy has to be supplied for the addition of second electron. The second electron gain enthalpy of an element is positive.

When an electron is added to oxygen atom to form  O¯ ion ,energy is released.But when another electron is added to O¯ ion to form O2- ion, the energy is absorbed to overcome the strong electrostatic repulsion between the negatively charged  O¯ ion and second electron being added.