Ch = sh = why and find the stuff
Answer:
C) 1 and 3
Explanation:
A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. ... Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law.
Hydrogen bonds<span> hold the paired nitrogenous bases together. Because </span>hydrogen bonds<span> are weak </span>bonds<span>, the two strands of </span>DNA<span> are easily separated a characteristic that is important to </span>DNA's<span> function.</span>Hydrogen bonds<span> form between adenine and thymine and between cytosine and guanine.</span>
Answer:

Explanation:
The work function of the sodium= 495.0 kJ/mol
It means that
1 mole of electrons can be removed by applying of 495.0 kJ of energy.
Also,
1 mole =
So,
electrons can be removed by applying of 495.0 kJ of energy.
1 electron can be removed by applying of
of energy.
Energy required =
Also,
1 kJ = 1000 J
So,
Energy required =
Also,
Where,
h is Plank's constant having value
c is the speed of light having value
So,
Also,
1 m = 10⁻⁹ nm
So,

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