What will come in the place of question mark (?) in the

In calcareous soil, effervescence is visible when treated with diluted 0.1 N HCl due to release of which of the following?

Which of the following property of soil is not influenced by tillage operations?

Local control is not applied for the design:

Tillers cut near base at 45° angle and developing buds or ripening grains chewed are the damaging symptoms of _____

In a vector having two or more target sites in a non essential portion of DNA for the cloning is known as ___

Which of the following is not correct about zero tillage?  

Conversion of rotary motion into mechanical power to move the vehicle wheels is done by

How is thermal efficiency different in diesel and petrol engines?

Fruit and shoot borer is an important pest of;