1pt The atomic mass and abundance of Si-28 is 27.977 amu and 92.2%. The atomic mass and abundance of Si-29 is 28.976 amu and 4.7%. The atomic mass and abundance of Si-30 is 29.974 amu and 3.1%. Which is the average atomic mass of silicon?
O A. 27.98 amu
OB. 28.09 amu
O c. 28.98 amu
OD. 29.97 amu

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

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.