Answer:
atom is the smallest indivisible particle of an element
Explanation:
The symbol of 20 element are H He li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca
element is the simplest pure form of a substance .
<span>1. D, 2. A, 3. B, 4. C, 5. D, 6. A, 7. B, 8.B....I think</span>
The energy released when electron move from n=4 to n=3 is 0.66 eV
We know that in an atom energy of nth state is
eV
where n is the energy level
Therefore,

Thus,
= -0.85eV
= -1.51eV
Therefore, total mount of energy released in moving electron from n=4 to n=3 is given by -

= -0.85 - ( -1.51)
= 0.66eV
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Answer:
<h3>Therefore, after long period of time 80kg of salt will remain in tank</h3>
Explanation:
given amount of salt at time t is A(t)
initial amount of salt =300 gm =0.3kg
=>A(0)=0.3
rate of salt inflow =5*0.4= 2 kg/min
rate of salt out flow =5*A/(200)=A/40
rate of change of salt at time t , dA/dt= rate of salt inflow- ratew of salt outflow

integrating factor

integrating factor 
multiply on both sides by 

integrate on both sides
b)
after long period of time means t - > ∞

<h3>Therefore, after long period of time 80kg of salt will remain in tank</h3>
Answer:
i cant see the whats in the picture