Q5) - They want the ionization energies of elements whose atomic no. increases starting from group 6. Take the following example:
Element : O F Ne Na Mg
Atomic no: 8 9 10 11 12
Configuration: 2:6 2:7 2:8 2:8:1 2:8:2
The trend shows that ionization energies increase upto Ne because atomic no. increases. This means that there are more electrons and hence there is a stronger nuclear attraction in the atoms. But after Ne, Ionization energies decreases because there is a 3rd subshell. This increases the distance between the 3rd valence electrons and the nucleus hence less nuclear attraction and hence less energy required to remove an electron from Na. Mg has more electrons than Na, so it must have a greater ionization energy. The pattern showing increasing ionization energies for the first 3 elements and less increasing ionization energies for the 4th and 5th element is C.
Q7) - I am not sure how to explain this. But I think its coz Mercury has a very low melting temperature and is a metal hence can conduct electricity in both liquid and solid state.
Q8) - The no. of atoms in H2O2 is 4, coz there are 2 hydrogen atoms and 2 oxygen atoms. Therefore, all you need to do is:
1 atom ----> 6.0x10^23 particles
4 atoms -----> ? = 4 X 6.0x10^23 = 2.4x10^24
Q9) - I am also not sure of this but this is how i think C is the answer.
Balanced equation if Mg is the metal:
Mg + Cl2 ----> MgCl2
According to mole ratio, Cl2 also is of 0.1 moles. Hence find the mass of Cl2 used ( 0.1x 35.5 x 2 = 7.1g).
Q10) - The gases in this equation are both NO2 and O2. Hence mole ratio respectively is 0.2 and 0.05. Total moles of gases is 0.25.
Therefore, Volume = 0.25x24 = 6.0dm3
Q16) - Try converting the skeletal formula to displayed formula:
Start counting from the smaller side. i.e if you start from the left the methyl group will be on Carbon 4 and 5, but from right side, they will be on 3 and 4. Always aim on counting from the smaller side. The parent chain has 7 carbons hence its a "Heptane". The name is 3,4- dimethylheptane. The 'di' is because there are 2 methyl groups in this molecule.
Sorry for the late reply. Hope that helped.