Questions

1) Former President - Pranab Mukherjee

2) Social activist Late - Nanaji Deshmukh

3) Singer Late - Bhupen Hazarika

were confirmed with the India's highest civilian honour Bharat Ratna for 2018.

A trade bloc is a type of intergovernmental agreement for a group of countries where barriers to trade are reduced or eliminated among the participating states and less competition and for economic integration.

New Delhi is the most polluted city in the world, according to Air Quality Index 2018.

Variable costs are expenses that vary in proportion to the amount of goods or services that a business produces. 

Examples of variable cost include labor, packaging and raw materials.

Foreign keys are the columns of a table that points to the primary key of another table. They act as a cross-reference between tables.

In detail : A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. In simpler words, the foreign key is defined in a second table, but it refers to the primary key or a unique key in the first table.