Answer - Ozone layer helps keep the harmful ultra violet rays hitting and keeping the atmospheric pressure in.
Reasoning - Without the ozone layer the whole planet would have a loss of water and especially people burning very easily from the sun. <span />
Answer:
crystal structure
Explanation:
A crystal structure is an ordered arrangement of atoms,ions or molecules in a regular repeating pattern,it is a form of solid state of matter and differs from liquid and gaseous states of matte in which the atoms or molecules are random or haphazard.
Döbereiner grouped the known elements into <em>triads</em> (sets of three) so that
• The <em>atomic mass of the middle element</em> was approximately the average of the other two
• The <em>chemical properties of the middle element</em> were between those of the other two
• The <em>physical properties of the middle element</em> were between those of the other two
One example of a triad is Li – Na – K.
(a) Atomic mass of Na = 23.0 u
Average atomic mass of Li and K = (6.9 u + 39.1 u)/2 = 46.0 u/2 = 23.0 u
(b) Li reacts slowly with water. Na reacts rapidly. Potassium reacts violently.
(c) Melting point of Na = 371 °C.
Average melting point of Li and K = (454 °C + 330 °C)/2 = 784 °C/2
= 392 °C
<u>Answer:</u> The correct answer is Option 2.
<u>Explanation:</u>
Centripetal force is defined as the force that acts on a body moving in a circular path and is directed towards the center around which the body is moving.
Mathematically,
Where,
= centripetal force
m = mass of the object
v = tangential velocity
r = radius of the path
From the above relation, X corresponds to the radius and Y corresponds to the tangential velocity.
Hence, the correct answer is option C.
