3. Measure: Select the Hardness test. Hardness is a measure of how easily a mineral can be scratched. It is measured on a scale of 1 to 10 called Mohs scale. If a mineral scratches a fingernail (hardness 2.5) but not a penny (3.5), its hardness is about 3.

relationships play a major role in a human's emotional and mental wellbeing. healthy relationships with the people around you are even linked to a smaller production of cortisol, a stress hormone.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: