Questions

A restrictive clause is one that limits the meaning of the word it describes.

For example :: 

The girl who lives next door is beautiful.

This restrictive clause limits "the girl" to say it's specifically the one next door.

Yes, a promise can be broken without being held.

Arunachal Pradesh State has been declared as the Open Defecation Free state.

Cosmology is the scientific study of the large scale properties of the universe as a whole. It endeavors to use the scientific method to understand the origin, evolution and ultimate fate of the entire Universe.

Depending on the outcome of the observations, the theories will need to be abandoned, revised or extended to accommodate the data. The prevailing theory about the origin and evolution of our Universe is the so-called Big Bang theory.

Income easticity of demand measures the responsiveness of demand for any goods to changes in income. With increase in incomes generally the demand for farm products like rice wheat etc, will not change drastically. With income increase, demand for luxuries such as consumer durables etc will increase. The income elasticity  of demand for farm products is thus low.