The suggestion is to prevent a puddle of the liquid present in the sample from forming or from it leaking on to the surface on which it is placed. For example, if precipitates of a solid are removed from water and then placed on filter paper to dry, the water will soak into the filter paper and then leak on to the counter on which it is placed. If this precipitate were placed in a watch glass or weighing paper, the water would only evaporate and would not contaminate the sample.
Answer:Lone pairs are the valence electron pair of any element which do not take part in bonding but affect the shape of molecules. Bond pairs or shared pairs are the electron pair which does both affect the geometry of molecules and take part in chemical bonding. These are form due to sharing of electrons.
Explanation:
ANSWER: B salt does not evaporate with water
Answer: The structure for the boron nitride molecule will be linear.
Explanation: When boron and nitrogen combine together to form a compound, the boron element will loose 3 electrons which will be easily accepted by the nitrogen element.
Boron : Atomic number is 5
Electronic configuration: 
To attain stable configuration, boron will loose 3 electrons easily.
Nitrogen : Atomic number is 7
Electronic configuration: 
To attain stable configuration. nitrogen will gain 3 electrons easily.
Hence, to form a molecule with these two elements, there will be 3 bonds present in between them and 1 pair of lone pair will be left on the nitrogen atom.
Structure of boron nitride ( which is linear) is attached in the image below.
Answer:
A.) the transfer of energy through a solid, such as the Earth’s crust
I hope this helps! ^-^
