What is a herbarium?

Study following statements regarding the preparation of herbarium sheets. (i) Plant should be collected in flowering stage. (ii) Every detail regarding the plant such sa locality, ecological conditions, vegetative and floral characters, etc. should be noted. (iii) Plants are evenly pressed by unfolding all the plant parts between blotting papers (or newspapers) with the help of plant pressers. (iv) Blotting papers need not be changed until the plant gets dried. (v) After drying, the plant specimen is carefully mounted/pasted on the herbarium sheets. (vi) The herbarium sheet is labelled on the lower right hand corner representing the number of plant specimen, data of collection, etc. Which of the above statements is/are correct ?

What is a thermodynamic system ? What are it’s types ?

What is a heat engine ? What are requisites for operating a heat engine ? What should be the characteristics of each part ?

What is equilibrium ? What are it's types. State their conditions for a body to be in equilibrium.

What is an Ammeter? What does it do?

What is aqua regia? What is its use ?