I believe the correct answer would be the last option. When an electrons moves from an excited state to the ground state, it would release energy. An electron in the excited state would mean that it contains high kinetic energy so to move to a lower state some of these energy should be released.
Answer:
Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at
Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at 1,064ºC and boils at 2,856ºC. Does boiling point depend on the mass present?
A. No; chemical properties stay the same regardless of mass.
B. No; physical properties stay the same regardless of mass.
C. Yes; physical properties can change when mass increases or decreases.
D. No; qualitative properties like boiling point stay the same regardless of mass.
Explanation:
Answer: 1. The ratio of the reactant aluminum to the product aluminum sulphate is 2:1
2. Option D. 1,3,2,2
Explanation: 1. From the balanced equation:
2Al + 3H2SO4 -> Al2(SO4)3 + 3H2
2moles of Al produced 1mole of Al2(SO4)3. Therefore, the ratio will be 2:1
2. C2H4 + 3O2 ---> 2CO2 + 2H2O from the equation, the coefficients are 1,3,2,2
The answer is

You must make sure each reactant has the same amount of subscripts on both sides of the equation.
Answer:
decreases going down within a group
Explanation:
Ionization energy of an atom is defined as the energy required to remove electron from the gaseous form the atom. The energy required to remove the highest placed electron in the gaseous form of an atom is referred to as the first ionization energy.
<em>In the periodic table, the </em><em>first ionization energy decreases down the group </em><em>because as the principal quantum number increases, the size of the orbital increases and the electron is easier to remove. </em>
<em>In addition, </em><em>the first ionization energy increases across the period </em><em>because electrons in the same principal quantum shell do not completely shield the increasing nuclear charge of the protons.</em>