A concave mirror is used in the design of solar furnaces because they converge the parallel sunrays at a point. This helps to increase the temperature of the furnace.
Metallic elements can exist on their own as individual atoms.
Nonmetals usually exist as molecules, combining with atoms of themselves.
Nonmetals can exist on their own as individual atoms.
Explanation:
Metallic elements can exist on their own as individual atoms. They have a large radius and are stable enough to freely exist as single atoms. The metallic bonding in them gives them stability. Example Gold, Silver, Platinum e.t.c
Non-metals are usually found in combined as state as molecules. They are usually joined together by covalent attraction. The bonds are formed with the atoms shares their valence electrons and their octet is completed. For example nitrogen gas, oxygen gas.
Most noble gases are non-metals that exist as individual mono-atomic gases on their own. The gases are stable and have an octet/duet configuration. For example helium gas, neon gas e.t.c
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I believe the answer is B)
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A common misconception is that scientific theories are rudimentary ideas that will eventually graduate into scientific laws when enough data and evidence have been accumulated. A theory does not change into a scientific law with the accumulation of new or better evidence.
p=3.0D contact lens is needed to correct his distant vision.
The person is suffering from myopia and hence need a concave lens to correct the defect. The lens should be such that an object at infinity must form its image at the far point.
Hence,f= -32.3cm
= -0.323m
we can define the power of the lens as the reciprocal of its focal length in metre.
The power of lens is the ability to converge and diverge rays of light.
The power of the lens can be obtained as:
p= 1/f
p=1/(-0.323)
p=3.0D
Thus,the power is 3.0D to correct his distant vision.
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