Question 20

an allotrope of carbon that is hard and is often used in jewelry is

a)diamond

b)graphite

c)quartz

d)silicon

Answer:    A)diamond

An allotrope of carbon that is mostly used in jewellery is diamond.

Explanation:

Allotropes of an element are the different physical forms in which the element can exist. These allotropes will have surprisingly different physical properties. Carbon has various allotropes like diamond, graphite and fullerene.

They differ in their physical appearance as well as physical properties. Accordingly they have differing uses.  Graphite is electrically conducting  while diamond  is a poor electrical conductor. Just like carbon many elements have varying number of allotropes.

metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (protoliths), without the protolith melting into liquid magma (a solid-state change). the change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. i hoped i !

explanation:

the universal gravitation equation. since the gravitational force is directly proportional to the mass of both interacting objects, more massive objects will attract each other with a greater gravitational force. if the mass of one of the objects is doubled, then the force of gravity between them is doubled.