Aparticular isotope of uranium has a nucleus with 92 protons and 143 neutrons identify this isotope in two diffrent ways

Isotopes can represented in two ways. In the first way, the element's symbol is used with mass number at the upper left and atomic number written on the lower left of the symbol. In the other form of representation, the isotope name is written with a dash and mass number.

Given that the isotope has 92 protons. So the atomic number is 92.

The isotope has 143 neutrons

So the mass number = Total number of protons + Neutrons

                                  = 92 + 143 = 235

Therefore, the two ways of representing the isotope is:

1.

2. Uranium-235

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.