Describe how to find the hardness of an unknown mineral?

By using a simple scratch test, you can determine the relative hardness of an unknown mineral. Select a fresh, clean surface on the specimen to be tested. Hold the specimen firmly and attempt to scratch it with the point of an object of known hardness. In this example, we use a sharp quartz (H=7) crystal .

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.