Answer : The energy of the photon emitted is, -12.1 eV
Explanation :
First we have to calculate the 
orbit of hydrogen atom.
Formula used :
where,
= energy of 
orbit
n = number of orbit
Z = atomic number of hydrogen atom = 1
Energy of n = 1 in an hydrogen atom:
Energy of n = 2 in an hydrogen atom:
Energy change transition from n = 1 to n = 3 occurs.
Let energy change be E.
The negative sign indicates that energy of the photon emitted.
Thus, the energy of the photon emitted is, -12.1 eV
Answer: Chosen landforms are:
1) Hill
2) Mountain
3) Plateau
4) Valley
Explanation:
1) Hill is an elevated location smaller than a mountain. Location: Land
2) Mountain is a large mass of earth and rock, rising above the common level of the earth or adjacent land, usually given by geographers as above 1000 feet in height (or 304.8 metres).
Location: Land or Water
3) Plateau is a largely level expanse of land at a high elevation. It is also known as tableland.
Location: Land
4) Valley is an elongated depression between hills or mountains, often with a river flowing through it.
Location: Land or Water
Nonpolar compound would be symmetrical
To determine the heat dissipated when a substance freezes, we multiply the heat of fusion of the substance to the mass of the substance that freezes. We calculate as follows:
Heat = -3.16 (64/32.06) = - 6.32 kJ
Hope this answers the question.
ionic bond:
Bond formed when an atom donates its electron and other atom receives those electrons.
polar covalent:
Bond formed by equal sharing of electrons between both the atoms and there is an electronegativity difference between the two atoms.
Nonpolar covalent:
Bond formed by equal sharing of electrons between both the atoms and there is no electronegativity difference between the two atoms.
Metallic:
Formed between two metals.
So the bond between :
Phosphorus and chlorine-polar covalent bond as it is formed by equal sharing of electrons between both the atoms and there is an electronegativity difference between the two atoms.
Potassium and oxygen -ionic bond as here potassium donates its electron and oxygen receives those electrons
Fluorine and fluorine -Non polar covalent bond as formed by equal sharing of electrons between both the atoms and there is no electronegativity difference between the two atoms.
Copper and aluminum-metallic bond as Formed between two metals.
Carbon and fluorine -polar covalent bond as it is formed by equal sharing of electrons between both the atoms and there is an electronegativity difference between the two atoms.
Carbon and hydrogen --Non polar covalent bond as formed by equal sharing of electrons between both the atoms and there is no electronegativity difference between the two atoms.
Aluminum and oxygen--ionic bond as here aluminum donates its electron and oxygen receives those electrons
Silver and copper --metallic bond as Formed between two metals.
