Prior to the spill, the mining waste holding pond was intended to temporarily hold water to allow time for particles to settle and the pH to be adjusted. Suppose the pond was used as intended, assuming no flow in or out. Cyanide (a common chemical used to extract gold from ore) is present in the pond at a concentration of 0.5 mg/L. Cyanide has a decay rate of 0.05/hr. What would the cyanide concentration be after 1 day of holding the water in the pond

0.15 mg/L

Explanation:

Decay is a first order process so;

ln[A] = ln[A]o - kt

[A]o = initial concentration = 0.5 mg/L

[A] = concentration at time t

t = time taken = 1 day = 24 hours

k = decay constant = 0.05/hr

ln[A] = ln(0.5) - 0.05(24)

ln[A] = -0.693  - 1.2

ln[A] = -1.893

e^ln[A] = e^-1.893

[A] = 0.15 mg/L

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.