Questions

Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. 

Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key.

• One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain.

True. Hormones are chemicals secreted and regulated by the endocrine system.

Nitrogen is found as a diatomic molecule (N2) in nature. There is a triple bond between the two nitrogen atoms.

The triple bond is pretty strong. Therefore, it needs a lot of energy to break those bonds and participate in a reaction. So nitrogen is commonly referred to as and used as an inert gas (high abundance & low cost.) However, it’s not truly inert like most noble gases. Nitrogen does react if the conditions are met. But those conditions are not exactly mild, but are not as extreme as for noble gases.

It forms nitric oxide and nitrogen dioxide with oxygen, ammonia with hydrogen, and nitrogen sulfide with sulfur.

Compressions and Rarefactions are characteristic of Longitudinal waves.

The direction of vibration of the particles is in the same plane as in which the wave is propagating. The particles vibrate back and forth, about their mean positions.