A. Less than 1% of the alpha particles went un-deflected through the gold foil.
Isotopes of the same element
₃₅⁷⁷X and ₃₅⁸¹X
<h3>Further explanation</h3>
Given
Isotopes of element
Required
Isotopes of the same element
Solution
The elements in nature have several types of isotopes
Isotopes are elements that have the same Atomic Number (Proton) and different mass numbers
Element symbols that meet the 2 conditions above are :
₃₅⁷⁷X and ₃₅⁸¹X
D) Chlorine, Cl. Hope that helped
Answer:

Explanation:
First, we find in the tables the ΔH of formation of each compound. As you can see in the (image 1)
Then we solve the ecuation for ΔH°reaction
ΔH°reaction=∑ΔH°f(products)−∑ΔH°f(Reactants)
ΔH°reaction= (-2* 393.5 - 2*285.8) - (52.4 + 0) kJ/mol
ΔH°reaction = -1.41 *10^3 kJ/mol