Lead is a toxic substance. the "normal" lead content in human blood is about 0.40 part per million (that is, 0.40 g of lead per million grams of blood). a value of 0.80 part per million (ppm) is considered to be dangerous. how many grams of lead are contained in 6.0 103 g of blood (the amount in an average adult) if the lead content is 0.66 ppm?

Answer : 0.0040 grams of lead is contained in the blood of an average adult human being.

Explnanation :

The lead content is given as 0.66 ppm.

That means there are 0.66 grams of lead in 1 million grams of blood.

Let us use this as a conversion factor as,

We have 6.0 x 10³ grams o blood. Te amount of lead in this is calculated as follows.

0.0040 grams of lead is contained in the blood of an average adult human being.

water   molecules stay close to each other through cohesion, the collective action of hydrogen bonds between water molecules. cohesion plants draw water upwards from the root through the stem's transport tubes (xylem) to the leaf. this transport occurs even in large trees and against gravity. transpiration, evaporation of water from plant leaves, creates a tension on water molecules being pulled up from the stem and roots.

water also has high (the attraction of one substance to another) properties because of its polar nature. adhesion of water molecules to plant cell walls counteract gravity while water is transported from roots to leaves.

water exhibits a very high surface tension when compared to other liquids. surface tension is a property of a liquid that holds the surface together and allows it to resist an external force. by capillary action, the water forms concave menisci inside the pores. the high surface tension of water pulls the concavity outwards, generating enough force to lift water from the roots to the leaves of plants.

thus, cohesion, along with adhesion and surface tension creates a capillary action that keeps water molecules interacting and moving through the plants out to the leaf cells.

therefore, option d) is the correct answer.

explanation:

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.