Answer: 1 mole ➡️ 6.022×10²³ atoms of si.
X mole ➡️ 2.8×10²⁴ atoms of si.
X = 2.8×10×10²³/6.022×10²³
= 28/6.022
= 4.65 moles.
Explanation:
Answer:
Electrons in atoms occupy energy levels, also called electron shells, outside the nucleus . Different shells can hold different maximum numbers of electrons. The electrons in an atom occupy the lowest available energy level first. This is the shell nearest the nucleus.
Explanation:
Answer : The enthalpy change for the reaction is, 201.9 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The balanced reaction of will be,
The intermediate balanced chemical reaction will be,
(1)
(2)
(3)
(4)
Now we will multiply the reaction 1 by 2, revere the reaction 2, reverse and half the reaction 3 and 4 then adding all the equations, we get :
(1)
(2)
(3)
(4)
The expression for enthalpy of the reaction will be,
Therefore, the enthalpy change for the reaction is, 201.9 kJ
Answer: Option A
Explanation: 2 Na + Cl2---> 2NaCl
Here Oxidation no of Na is zero while in NaCl is +1. That means oxidation state of Na increased from 0 to +1 hence oxidation
While Cl2 has zero in molecular form and -1 in NaCl hence Reduction (Oxidation no decreased from zero to -1)
Halogens(cl) always shows -1 oxidation state and IA group elements(Na)shows +1 oxidation state
The answer is hydroiodic acid.