What is the least concentration of an element that could be detected in plants, using modern techniques.

What is plasma? Which property of gases help us in detecting the leakage of LPG?

A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a SONAR the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be 77.0 s. What is the distance of the enemy submarine? (Speed of sound in water = 1450 m s^(-1) )

Concentrated nitric acid used in laboratory work is 68% nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g mL^-1 ?

Describe transpiration pull model of water transport in plants. What are the factors influencing transpiration? How is it useful to plants?

If a plant shows a symptom which could develop due to deficiency of more than one nutrient, how would you find out experimentally, the real deficient mineral element?

What are commonly used techniques used by farmers in village to purify food grains?