5 Protons {+}
5 Electrons {-}
6 Neutrons {0}
What element is this ?

boron

Explanation:

The mass number of an atom : a. 11

Further explanation  

The Atomic Number (Z) indicates the number of protons in an atom of an element. If the atom is neutral then the number of protons will be equal to the number of electrons. So the atomic number can also indicate the number of electrons.  

So atomic number = number of protons = number of electrons  

Mass Number (A) is the sum of protons and neutrons  

Mass Number (A) = Number of protons + Number of Neutrons  

So that the relationship between atomic numbers and mass numbers can be formulated as follows:  

Atomic Number (Z) = Mass Number (A) - Number of Neutrons  

An atom has 5 protons, 5 electrons and 6 neutrons

The atomic number = number of protons = number of electrons = 5

The mass number = 5 protons + 6 neutrons = 11

The possible atom in question is Boron (B)

So the  element notation,

Learn more  

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it is a solid

explanation:

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.